diff --git a/common/cleanup_previous_update_action_delegate.h b/common/cleanup_previous_update_action_delegate.h
index 7dad9c5..8daf860 100644
--- a/common/cleanup_previous_update_action_delegate.h
+++ b/common/cleanup_previous_update_action_delegate.h
@@ -14,8 +14,8 @@
 // limitations under the License.
 //
 
-#ifndef UPDATE_ENGINE_CLEANUP_PREVIOUS_UPDATE_ACTION_DELEGETE_H_
-#define UPDATE_ENGINE_CLEANUP_PREVIOUS_UPDATE_ACTION_DELEGETE_H_
+#ifndef UPDATE_ENGINE_COMMON_CLEANUP_PREVIOUS_UPDATE_ACTION_DELEGETE_H_
+#define UPDATE_ENGINE_COMMON_CLEANUP_PREVIOUS_UPDATE_ACTION_DELEGETE_H_
 
 namespace chromeos_update_engine {
 
@@ -29,4 +29,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // UPDATE_ENGINE_CLEANUP_PREVIOUS_UPDATE_ACTION_DELEGETE_H_
+#endif  // UPDATE_ENGINE_COMMON_CLEANUP_PREVIOUS_UPDATE_ACTION_DELEGETE_H_
diff --git a/common/connection_utils.cc b/common/connection_utils.cc
new file mode 100644
index 0000000..44e5128
--- /dev/null
+++ b/common/connection_utils.cc
@@ -0,0 +1,72 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "update_engine/common/connection_utils.h"
+
+#include <shill/dbus-constants.h>
+
+namespace {
+// Not defined by shill since we don't use this outside of UE.
+constexpr char kTypeDisconnected[] = "Disconnected";
+constexpr char kTypeUnknown[] = "Unknown";
+}  // namespace
+
+namespace chromeos_update_engine {
+namespace connection_utils {
+
+ConnectionType ParseConnectionType(const std::string& type_str) {
+  if (type_str == shill::kTypeEthernet) {
+    return ConnectionType::kEthernet;
+  } else if (type_str == shill::kTypeWifi) {
+    return ConnectionType::kWifi;
+  } else if (type_str == shill::kTypeCellular) {
+    return ConnectionType::kCellular;
+  } else if (type_str == kTypeDisconnected) {
+    return ConnectionType::kDisconnected;
+  }
+  return ConnectionType::kUnknown;
+}
+
+ConnectionTethering ParseConnectionTethering(const std::string& tethering_str) {
+  if (tethering_str == shill::kTetheringNotDetectedState) {
+    return ConnectionTethering::kNotDetected;
+  } else if (tethering_str == shill::kTetheringSuspectedState) {
+    return ConnectionTethering::kSuspected;
+  } else if (tethering_str == shill::kTetheringConfirmedState) {
+    return ConnectionTethering::kConfirmed;
+  }
+  return ConnectionTethering::kUnknown;
+}
+
+const char* StringForConnectionType(ConnectionType type) {
+  switch (type) {
+    case ConnectionType::kEthernet:
+      return shill::kTypeEthernet;
+    case ConnectionType::kWifi:
+      return shill::kTypeWifi;
+    case ConnectionType::kCellular:
+      return shill::kTypeCellular;
+    case ConnectionType::kDisconnected:
+      return kTypeDisconnected;
+    case ConnectionType::kUnknown:
+      return kTypeUnknown;
+  }
+  return kTypeUnknown;
+}
+
+}  // namespace connection_utils
+
+}  // namespace chromeos_update_engine
diff --git a/common/connection_utils.h b/common/connection_utils.h
new file mode 100644
index 0000000..5d63fb2
--- /dev/null
+++ b/common/connection_utils.h
@@ -0,0 +1,50 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_CONNECTION_UTILS_H_
+#define UPDATE_ENGINE_COMMON_CONNECTION_UTILS_H_
+
+#include <string>
+
+namespace chromeos_update_engine {
+
+enum class ConnectionType {
+  kDisconnected,
+  kEthernet,
+  kWifi,
+  kCellular,
+  kUnknown
+};
+
+enum class ConnectionTethering {
+  kNotDetected,
+  kSuspected,
+  kConfirmed,
+  kUnknown,
+};
+
+namespace connection_utils {
+// Helper methods for converting shill strings into symbolic values.
+ConnectionType ParseConnectionType(const std::string& type_str);
+ConnectionTethering ParseConnectionTethering(const std::string& tethering_str);
+
+// Returns the string representation corresponding to the given connection type.
+const char* StringForConnectionType(ConnectionType type);
+}  // namespace connection_utils
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_CONNECTION_UTILS_H_
diff --git a/common/daemon_base.h b/common/daemon_base.h
new file mode 100644
index 0000000..4bc5ef7
--- /dev/null
+++ b/common/daemon_base.h
@@ -0,0 +1,40 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_DAEMON_BASE_H_
+#define UPDATE_ENGINE_COMMON_DAEMON_BASE_H_
+
+#include <memory>
+
+#include <brillo/daemons/daemon.h>
+
+namespace chromeos_update_engine {
+
+class DaemonBase : public brillo::Daemon {
+ public:
+  DaemonBase() = default;
+  virtual ~DaemonBase() = default;
+
+  // Creates an instance of the daemon.
+  static std::unique_ptr<DaemonBase> CreateInstance();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DaemonBase);
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_DAEMON_BASE_H_
diff --git a/common/daemon_state_interface.h b/common/daemon_state_interface.h
new file mode 100644
index 0000000..9509fa2
--- /dev/null
+++ b/common/daemon_state_interface.h
@@ -0,0 +1,49 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_DAEMON_STATE_INTERFACE_H_
+#define UPDATE_ENGINE_COMMON_DAEMON_STATE_INTERFACE_H_
+
+#include "update_engine/common/service_observer_interface.h"
+
+#include <memory>
+#include <set>
+
+namespace chromeos_update_engine {
+
+class DaemonStateInterface {
+ public:
+  virtual ~DaemonStateInterface() = default;
+
+  // Start the daemon loop. Should be called only once to start the daemon's
+  // main functionality.
+  virtual bool StartUpdater() = 0;
+
+  // Add and remove an observer. All the registered observers will be called
+  // whenever there's a new status to update.
+  virtual void AddObserver(ServiceObserverInterface* observer) = 0;
+  virtual void RemoveObserver(ServiceObserverInterface* observer) = 0;
+
+  // Return the set of current observers.
+  virtual const std::set<ServiceObserverInterface*>& service_observers() = 0;
+
+ protected:
+  DaemonStateInterface() = default;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_DAEMON_STATE_INTERFACE_H_
diff --git a/common/download_action.h b/common/download_action.h
new file mode 100644
index 0000000..c167c2d
--- /dev/null
+++ b/common/download_action.h
@@ -0,0 +1,203 @@
+//
+// Copyright (C) 2011 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_DOWNLOAD_ACTION_H_
+#define UPDATE_ENGINE_COMMON_DOWNLOAD_ACTION_H_
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <memory>
+#include <string>
+
+#include "update_engine/common/action.h"
+#include "update_engine/common/boot_control_interface.h"
+#include "update_engine/common/http_fetcher.h"
+#include "update_engine/common/multi_range_http_fetcher.h"
+#include "update_engine/common/system_state.h"
+#include "update_engine/payload_consumer/delta_performer.h"
+#include "update_engine/payload_consumer/install_plan.h"
+
+// The Download Action downloads a specified url to disk. The url should point
+// to an update in a delta payload format. The payload will be piped into a
+// DeltaPerformer that will apply the delta to the disk.
+
+namespace chromeos_update_engine {
+
+class DownloadActionDelegate {
+ public:
+  virtual ~DownloadActionDelegate() = default;
+
+  // Called periodically after bytes are received. This method will be invoked
+  // only if the DownloadAction is running. |bytes_progressed| is the number of
+  // bytes downloaded since the last call of this method, |bytes_received|
+  // the number of bytes downloaded thus far and |total| is the number of bytes
+  // expected.
+  virtual void BytesReceived(uint64_t bytes_progressed,
+                             uint64_t bytes_received,
+                             uint64_t total) = 0;
+
+  // Returns whether the download should be canceled, in which case the
+  // |cancel_reason| error should be set to the reason why the download was
+  // canceled.
+  virtual bool ShouldCancel(ErrorCode* cancel_reason) = 0;
+
+  // Called once the complete payload has been downloaded. Note that any errors
+  // while applying or downloading the partial payload will result in this
+  // method not being called.
+  virtual void DownloadComplete() = 0;
+};
+
+class PrefsInterface;
+
+class DownloadAction : public InstallPlanAction, public HttpFetcherDelegate {
+ public:
+  // Debugging/logging
+  static std::string StaticType() { return "DownloadAction"; }
+
+  // Takes ownership of the passed in HttpFetcher. Useful for testing.
+  // A good calling pattern is:
+  // DownloadAction(prefs, boot_contol, hardware, system_state,
+  //                new WhateverHttpFetcher, false);
+  DownloadAction(PrefsInterface* prefs,
+                 BootControlInterface* boot_control,
+                 HardwareInterface* hardware,
+                 SystemState* system_state,
+                 HttpFetcher* http_fetcher,
+                 bool interactive);
+  ~DownloadAction() override;
+
+  // InstallPlanAction overrides.
+  void PerformAction() override;
+  void SuspendAction() override;
+  void ResumeAction() override;
+  void TerminateProcessing() override;
+  std::string Type() const override { return StaticType(); }
+
+  // Testing
+  void SetTestFileWriter(FileWriter* writer) { writer_ = writer; }
+
+  int GetHTTPResponseCode() { return http_fetcher_->http_response_code(); }
+
+  // HttpFetcherDelegate methods (see http_fetcher.h)
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override;
+  void SeekToOffset(off_t offset) override;
+  void TransferComplete(HttpFetcher* fetcher, bool successful) override;
+  void TransferTerminated(HttpFetcher* fetcher) override;
+
+  DownloadActionDelegate* delegate() const { return delegate_; }
+  void set_delegate(DownloadActionDelegate* delegate) { delegate_ = delegate; }
+
+  void set_base_offset(int64_t base_offset) { base_offset_ = base_offset; }
+
+  HttpFetcher* http_fetcher() { return http_fetcher_.get(); }
+
+  // Returns the p2p file id for the file being written or the empty
+  // string if we're not writing to a p2p file.
+  std::string p2p_file_id() { return p2p_file_id_; }
+
+ private:
+  // Closes the file descriptor for the p2p file being written and
+  // clears |p2p_file_id_| to indicate that we're no longer sharing
+  // the file. If |delete_p2p_file| is True, also deletes the file.
+  // If there is no p2p file descriptor, this method does nothing.
+  void CloseP2PSharingFd(bool delete_p2p_file);
+
+  // Starts sharing the p2p file. Must be called before
+  // WriteToP2PFile(). Returns True if this worked.
+  bool SetupP2PSharingFd();
+
+  // Writes |length| bytes of payload from |data| into |file_offset|
+  // of the p2p file. Also does validation checks; for example ensures we
+  // don't end up with a file with holes in it.
+  //
+  // This method does nothing if SetupP2PSharingFd() hasn't been
+  // called or if CloseP2PSharingFd() has been called.
+  void WriteToP2PFile(const void* data, size_t length, off_t file_offset);
+
+  // Attempt to load cached manifest data from prefs
+  // return true on success, false otherwise.
+  bool LoadCachedManifest(int64_t manifest_size);
+
+  // Start downloading the current payload using delta_performer.
+  void StartDownloading();
+
+  // Pointer to the current payload in install_plan_.payloads.
+  InstallPlan::Payload* payload_{nullptr};
+
+  // SystemState required pointers.
+  PrefsInterface* prefs_;
+  BootControlInterface* boot_control_;
+  HardwareInterface* hardware_;
+
+  // Global context for the system.
+  SystemState* system_state_;
+
+  // Pointer to the MultiRangeHttpFetcher that does the http work.
+  std::unique_ptr<MultiRangeHttpFetcher> http_fetcher_;
+
+  // If |true|, the update is user initiated (vs. periodic update checks). Hence
+  // the |delta_performer_| can decide not to use O_DSYNC flag for faster
+  // update.
+  bool interactive_;
+
+  // The FileWriter that downloaded data should be written to. It will
+  // either point to *decompressing_file_writer_ or *delta_performer_.
+  FileWriter* writer_;
+
+  std::unique_ptr<DeltaPerformer> delta_performer_;
+
+  // Used by TransferTerminated to figure if this action terminated itself or
+  // was terminated by the action processor.
+  ErrorCode code_;
+
+  // For reporting status to outsiders
+  DownloadActionDelegate* delegate_;
+  uint64_t bytes_received_{0};  // per file/range
+  uint64_t bytes_received_previous_payloads_{0};
+  uint64_t bytes_total_{0};
+  bool download_active_{false};
+
+  // The file-id for the file we're sharing or the empty string
+  // if we're not using p2p to share.
+  std::string p2p_file_id_;
+
+  // The file descriptor for the p2p file used for caching the payload or -1
+  // if we're not using p2p to share.
+  int p2p_sharing_fd_;
+
+  // Set to |false| if p2p file is not visible.
+  bool p2p_visible_;
+
+  // Loaded from prefs before downloading any payload.
+  size_t resume_payload_index_{0};
+
+  // Offset of the payload in the download URL, used by UpdateAttempterAndroid.
+  int64_t base_offset_{0};
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadAction);
+};
+
+// We want to be sure that we're compiled with large file support on linux,
+// just in case we find ourselves downloading large images.
+static_assert(8 == sizeof(off_t), "off_t not 64 bit");
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_DOWNLOAD_ACTION_H_
diff --git a/common/http_fetcher.h b/common/http_fetcher.h
index f74a0f0..7fa5f09 100644
--- a/common/http_fetcher.h
+++ b/common/http_fetcher.h
@@ -28,8 +28,8 @@
 #include <brillo/message_loops/message_loop.h>
 
 #include "update_engine/common/http_common.h"
+#include "update_engine/common/metrics_constants.h"
 #include "update_engine/common/proxy_resolver.h"
-#include "update_engine/metrics_constants.h"
 
 // This class is a simple wrapper around an HTTP library (libcurl). We can
 // easily mock out this interface for testing.
diff --git a/common/logging.h b/common/logging.h
new file mode 100644
index 0000000..c9e7483
--- /dev/null
+++ b/common/logging.h
@@ -0,0 +1,23 @@
+//
+// Copyright (C) 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+namespace chromeos_update_engine {
+
+// Set up logging. |log_to_system| and |log_to_file| specifies
+// the destination of logs.
+void SetupLogging(bool log_to_system, bool log_to_file);
+
+}  // namespace chromeos_update_engine
diff --git a/common/metrics_constants.h b/common/metrics_constants.h
new file mode 100644
index 0000000..b7633b9
--- /dev/null
+++ b/common/metrics_constants.h
@@ -0,0 +1,147 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_METRICS_CONSTANTS_H_
+#define UPDATE_ENGINE_COMMON_METRICS_CONSTANTS_H_
+
+namespace chromeos_update_engine {
+
+namespace metrics {
+// The possible outcomes when checking for updates.
+//
+// This is used in the UpdateEngine.Check.Result histogram.
+enum class CheckResult {
+  kUpdateAvailable,    // Response indicates an update is available.
+  kNoUpdateAvailable,  // Response indicates no updates are available.
+  kDownloadError,      // Error downloading response from Omaha.
+  kParsingError,       // Error parsing response.
+  kRebootPending,      // No update check was performed a reboot is pending.
+
+  kNumConstants,
+  kUnset = -1
+};
+
+// Possible ways a device can react to a new update being available.
+//
+// This is used in the UpdateEngine.Check.Reaction histogram.
+enum class CheckReaction {
+  kUpdating,    // Device proceeds to download and apply update.
+  kIgnored,     // Device-policy dictates ignoring the update.
+  kDeferring,   // Device-policy dictates waiting.
+  kBackingOff,  // Previous errors dictates waiting.
+
+  kNumConstants,
+  kUnset = -1
+};
+
+// The possible ways that downloading from a HTTP or HTTPS server can fail.
+//
+// This is used in the UpdateEngine.Check.DownloadErrorCode and
+// UpdateEngine.Attempt.DownloadErrorCode histograms.
+enum class DownloadErrorCode {
+  // Errors that can happen in the field. See http://crbug.com/355745
+  // for how we plan to add more detail in the future.
+  kDownloadError = 0,  // Error downloading data from server.
+
+  // IMPORTANT: When adding a new error code, add at the bottom of the
+  // above block and before the kInputMalformed field. This
+  // is to ensure that error codes are not reordered.
+
+  // This error is reported when libcurl returns CURLE_COULDNT_RESOLVE_HOST and
+  // calling res_init() can recover.
+  kUnresolvedHostRecovered = 97,
+  // This error is reported when libcurl returns CURLE_COULDNT_RESOLVE_HOST.
+  kUnresolvedHostError = 98,
+  // This error is reported when libcurl has an internal error that
+  // update_engine can't recover from.
+  kInternalLibCurlError = 99,
+
+  // This error code is used to convey that malformed input was given
+  // to the utils::GetDownloadErrorCode() function. This should never
+  // happen but if it does it's because of an internal update_engine
+  // error and we're interested in knowing this.
+  kInputMalformed = 100,
+
+  // Bucket for capturing HTTP status codes not in the 200-599
+  // range. This should never happen in practice but if it does we
+  // want to know.
+  kHttpStatusOther = 101,
+
+  // Above 200 and below 600, the value is the HTTP status code.
+  kHttpStatus200 = 200,
+
+  kNumConstants = 600,
+
+  kUnset = -1
+};
+
+// Possible ways an update attempt can end.
+//
+// This is used in the UpdateEngine.Attempt.Result histogram.
+enum class AttemptResult {
+  kUpdateSucceeded,             // The update succeeded.
+  kInternalError,               // An internal error occurred.
+  kPayloadDownloadError,        // Failure while downloading payload.
+  kMetadataMalformed,           // Metadata was malformed.
+  kOperationMalformed,          // An operation was malformed.
+  kOperationExecutionError,     // An operation failed to execute.
+  kMetadataVerificationFailed,  // Metadata verification failed.
+  kPayloadVerificationFailed,   // Payload verification failed.
+  kVerificationFailed,          // Root or Kernel partition verification failed.
+  kPostInstallFailed,           // The postinstall step failed.
+  kAbnormalTermination,         // The attempt ended abnormally.
+  kUpdateCanceled,              // Update canceled by the user.
+  kUpdateSucceededNotActive,    // Update succeeded but the new slot is not
+                                // active.
+  kUpdateSkipped,               // Current update skipped.
+  kNumConstants,
+
+  kUnset = -1
+};
+
+// Possible ways the device is connected to the Internet.
+//
+// This is used in the UpdateEngine.Attempt.ConnectionType histogram.
+enum class ConnectionType {
+  kUnknown = 0,           // Unknown.
+  kEthernet = 1,          // Ethernet.
+  kWifi = 2,              // Wireless.
+  kCellular = 5,          // Cellular.
+  kTetheredEthernet = 6,  // Tethered (Ethernet).
+  kTetheredWifi = 7,      // Tethered (Wifi).
+  kDisconnected = 8,      // Disconnected.
+  // deprecated: kWimax = 3,
+  // deprecated: kBluetooth = 4,
+
+  kNumConstants,
+  kUnset = -1
+};
+
+// Possible ways a rollback can end.
+//
+// This is used in the UpdateEngine.Rollback histogram.
+enum class RollbackResult {
+  kFailed,
+  kSuccess,
+
+  kNumConstants
+};
+
+}  // namespace metrics
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_METRICS_CONSTANTS_H_
diff --git a/common/metrics_reporter_interface.h b/common/metrics_reporter_interface.h
new file mode 100644
index 0000000..d7c5347
--- /dev/null
+++ b/common/metrics_reporter_interface.h
@@ -0,0 +1,247 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_METRICS_REPORTER_INTERFACE_H_
+#define UPDATE_ENGINE_COMMON_METRICS_REPORTER_INTERFACE_H_
+
+#include <memory>
+#include <string>
+
+#include <base/time/time.h>
+
+#include "update_engine/common/constants.h"
+#include "update_engine/common/error_code.h"
+#include "update_engine/common/metrics_constants.h"
+#include "update_engine/common/system_state.h"
+
+namespace chromeos_update_engine {
+
+enum class ServerToCheck;
+enum class CertificateCheckResult;
+
+namespace metrics {
+
+std::unique_ptr<MetricsReporterInterface> CreateMetricsReporter();
+
+}  // namespace metrics
+
+class MetricsReporterInterface {
+ public:
+  virtual ~MetricsReporterInterface() = default;
+
+  // Helper function to report metrics related to user-initiated rollback. The
+  // following metrics are reported:
+  //
+  //  |kMetricRollbackResult|
+  virtual void ReportRollbackMetrics(metrics::RollbackResult result) = 0;
+
+  // Helper function to report metrics related to enterprise (admin-initiated)
+  // rollback:
+  //
+  //  |kMetricEnterpriseRollbackSuccess|
+  //  |kMetricEnterpriseRollbackFailure|
+  virtual void ReportEnterpriseRollbackMetrics(
+      bool success, const std::string& rollback_version) = 0;
+
+  // Helper function to report metrics reported once a day. The
+  // following metrics are reported:
+  //
+  //  |kMetricDailyOSAgeDays|
+  virtual void ReportDailyMetrics(base::TimeDelta os_age) = 0;
+
+  // Helper function to report metrics after completing an update check
+  // with the ChromeOS update server ("Omaha"). The following metrics
+  // are reported:
+  //
+  //  |kMetricCheckResult|
+  //  |kMetricCheckReaction|
+  //  |kMetricCheckDownloadErrorCode|
+  //  |kMetricCheckTimeSinceLastCheckMinutes|
+  //  |kMetricCheckTimeSinceLastCheckUptimeMinutes|
+  //  |kMetricCheckTargetVersion|
+  //  |kMetricCheckRollbackTargetVersion|
+  //
+  // The |kMetricCheckResult| metric will only be reported if |result|
+  // is not |kUnset|.
+  //
+  // The |kMetricCheckReaction| metric will only be reported if
+  // |reaction| is not |kUnset|.
+  //
+  // The |kMetricCheckDownloadErrorCode| will only be reported if
+  // |download_error_code| is not |kUnset|.
+  //
+  // The values for the |kMetricCheckTimeSinceLastCheckMinutes| and
+  // |kMetricCheckTimeSinceLastCheckUptimeMinutes| metrics are
+  // automatically reported and calculated by maintaining persistent
+  // and process-local state variables.
+  //
+  // |kMetricCheckTargetVersion| reports the first section of the target version
+  // if it's set, |kMetricCheckRollbackTargetVersion| reports the same, but only
+  // if rollback is also allowed using enterprise policy.
+  virtual void ReportUpdateCheckMetrics(
+      SystemState* system_state,
+      metrics::CheckResult result,
+      metrics::CheckReaction reaction,
+      metrics::DownloadErrorCode download_error_code) = 0;
+
+  // Helper function to report metrics after the completion of each
+  // update attempt. The following metrics are reported:
+  //
+  //  |kMetricAttemptNumber|
+  //  |kMetricAttemptPayloadType|
+  //  |kMetricAttemptPayloadSizeMiB|
+  //  |kMetricAttemptDurationMinutes|
+  //  |kMetricAttemptDurationUptimeMinutes|
+  //  |kMetricAttemptTimeSinceLastAttemptMinutes|
+  //  |kMetricAttemptTimeSinceLastAttemptUptimeMinutes|
+  //  |kMetricAttemptResult|
+  //  |kMetricAttemptInternalErrorCode|
+  //
+  // The |kMetricAttemptInternalErrorCode| metric will only be reported
+  // if |internal_error_code| is not |kErrorSuccess|.
+  //
+  // The |kMetricAttemptDownloadErrorCode| metric will only be
+  // reported if |payload_download_error_code| is not |kUnset|.
+  //
+  // The values for the |kMetricAttemptTimeSinceLastAttemptMinutes| and
+  // |kMetricAttemptTimeSinceLastAttemptUptimeMinutes| metrics are
+  // automatically calculated and reported by maintaining persistent and
+  // process-local state variables.
+  virtual void ReportUpdateAttemptMetrics(SystemState* system_state,
+                                          int attempt_number,
+                                          PayloadType payload_type,
+                                          base::TimeDelta duration,
+                                          base::TimeDelta duration_uptime,
+                                          int64_t payload_size,
+                                          metrics::AttemptResult attempt_result,
+                                          ErrorCode internal_error_code) = 0;
+
+  // Helper function to report download metrics after the completion of each
+  // update attempt. The following metrics are reported:
+  //
+  // |kMetricAttemptPayloadBytesDownloadedMiB|
+  // |kMetricAttemptPayloadDownloadSpeedKBps|
+  // |kMetricAttemptDownloadSource|
+  // |kMetricAttemptDownloadErrorCode|
+  // |kMetricAttemptConnectionType|
+  virtual void ReportUpdateAttemptDownloadMetrics(
+      int64_t payload_bytes_downloaded,
+      int64_t payload_download_speed_bps,
+      DownloadSource download_source,
+      metrics::DownloadErrorCode payload_download_error_code,
+      metrics::ConnectionType connection_type) = 0;
+
+  // Reports the |kAbnormalTermination| for the |kMetricAttemptResult|
+  // metric. No other metrics in the UpdateEngine.Attempt.* namespace
+  // will be reported.
+  virtual void ReportAbnormallyTerminatedUpdateAttemptMetrics() = 0;
+
+  // Helper function to report the after the completion of a successful
+  // update attempt. The following metrics are reported:
+  //
+  //  |kMetricSuccessfulUpdateAttemptCount|
+  //  |kMetricSuccessfulUpdateUpdatesAbandonedCount|
+  //  |kMetricSuccessfulUpdatePayloadType|
+  //  |kMetricSuccessfulUpdatePayloadSizeMiB|
+  //  |kMetricSuccessfulUpdateBytesDownloadedMiBHttpsServer|
+  //  |kMetricSuccessfulUpdateBytesDownloadedMiBHttpServer|
+  //  |kMetricSuccessfulUpdateBytesDownloadedMiBHttpPeer|
+  //  |kMetricSuccessfulUpdateBytesDownloadedMiB|
+  //  |kMetricSuccessfulUpdateDownloadSourcesUsed|
+  //  |kMetricSuccessfulUpdateDownloadOverheadPercentage|
+  //  |kMetricSuccessfulUpdateTotalDurationMinutes|
+  //  |kMetricSuccessfulUpdateTotalDurationUptimeMinutes|
+  //  |kMetricSuccessfulUpdateRebootCount|
+  //  |kMetricSuccessfulUpdateUrlSwitchCount|
+  //
+  // The values for the |kMetricSuccessfulUpdateDownloadSourcesUsed| are
+  // |kMetricSuccessfulUpdateBytesDownloadedMiB| metrics automatically
+  // calculated from examining the |num_bytes_downloaded| array.
+  virtual void ReportSuccessfulUpdateMetrics(
+      int attempt_count,
+      int updates_abandoned_count,
+      PayloadType payload_type,
+      int64_t payload_size,
+      int64_t num_bytes_downloaded[kNumDownloadSources],
+      int download_overhead_percentage,
+      base::TimeDelta total_duration,
+      base::TimeDelta total_duration_uptime,
+      int reboot_count,
+      int url_switch_count) = 0;
+
+  // Helper function to report the after the completion of a SSL certificate
+  // check. One of the following metrics is reported:
+  //
+  //  |kMetricCertificateCheckUpdateCheck|
+  //  |kMetricCertificateCheckDownload|
+  virtual void ReportCertificateCheckMetrics(ServerToCheck server_to_check,
+                                             CertificateCheckResult result) = 0;
+
+  // Helper function to report the number failed update attempts. The following
+  // metrics are reported:
+  //
+  // |kMetricFailedUpdateCount|
+  virtual void ReportFailedUpdateCount(int target_attempt) = 0;
+
+  // Helper function to report the time interval in minutes between a
+  // successful update and the reboot into the updated system. The following
+  // metrics are reported:
+  //
+  // |kMetricTimeToRebootMinutes|
+  virtual void ReportTimeToReboot(int time_to_reboot_minutes) = 0;
+
+  // Helper function to report the source of installation data. The following
+  // metrics are reported:
+  //
+  // |kMetricInstallDateProvisioningSource|
+  virtual void ReportInstallDateProvisioningSource(int source, int max) = 0;
+
+  // Helper function to report an internal error code. The following metrics are
+  // reported:
+  //
+  // |kMetricAttemptInternalErrorCode|
+  virtual void ReportInternalErrorCode(ErrorCode error_code) = 0;
+
+  // Helper function to report metrics related to the verified boot key
+  // versions:
+  //
+  //  |kMetricKernelMinVersion|
+  //  |kMetricKernelMaxRollforwardVersion|
+  //  |kMetricKernelMaxRollforwardSetSuccess|
+  virtual void ReportKeyVersionMetrics(int kernel_min_version,
+                                       int kernel_max_rollforward_version,
+                                       bool kernel_max_rollforward_success) = 0;
+
+  // Helper function to report the duration between an update being seen by the
+  // client to the update being applied. Updates are not always immediately
+  // applied when seen, several enterprise policies can affect when an update
+  // would actually be downloaded and applied.
+  //
+  // This metric should only be reported for enterprise enrolled devices.
+  //
+  // The following metrics are reported from this function:
+  //   If |has_time_restriction_policy| is false:
+  //     |kMetricSuccessfulUpdateDurationFromSeenDays|
+  //   If |has_time_restriction_policy| is true:
+  //     |kMetricSuccessfulUpdateDurationFromSeenTimeRestrictedDays|
+  //
+  virtual void ReportEnterpriseUpdateSeenToDownloadDays(
+      bool has_time_restriction_policy, int time_to_update_days) = 0;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_METRICS_REPORTER_INTERFACE_H_
diff --git a/common/metrics_reporter_stub.cc b/common/metrics_reporter_stub.cc
new file mode 100644
index 0000000..dcb4e8c
--- /dev/null
+++ b/common/metrics_reporter_stub.cc
@@ -0,0 +1,31 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "update_engine/common/metrics_reporter_stub.h"
+
+#include <memory>
+
+namespace chromeos_update_engine {
+
+namespace metrics {
+
+std::unique_ptr<MetricsReporterInterface> CreateMetricsReporter() {
+  return std::make_unique<MetricsReporterStub>();
+}
+
+}  // namespace metrics
+
+}  // namespace chromeos_update_engine
diff --git a/common/metrics_reporter_stub.h b/common/metrics_reporter_stub.h
new file mode 100644
index 0000000..1470aaa
--- /dev/null
+++ b/common/metrics_reporter_stub.h
@@ -0,0 +1,101 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_METRICS_REPORTER_STUB_H_
+#define UPDATE_ENGINE_COMMON_METRICS_REPORTER_STUB_H_
+
+#include <string>
+
+#include "update_engine/common/error_code.h"
+#include "update_engine/common/metrics_constants.h"
+#include "update_engine/common/metrics_reporter_interface.h"
+
+namespace chromeos_update_engine {
+
+class MetricsReporterStub : public MetricsReporterInterface {
+ public:
+  MetricsReporterStub() = default;
+
+  ~MetricsReporterStub() override = default;
+
+  void ReportRollbackMetrics(metrics::RollbackResult result) override {}
+
+  void ReportEnterpriseRollbackMetrics(
+      bool success, const std::string& rollback_version) override {}
+
+  void ReportDailyMetrics(base::TimeDelta os_age) override {}
+
+  void ReportUpdateCheckMetrics(
+      SystemState* system_state,
+      metrics::CheckResult result,
+      metrics::CheckReaction reaction,
+      metrics::DownloadErrorCode download_error_code) override {}
+
+  void ReportUpdateAttemptMetrics(SystemState* system_state,
+                                  int attempt_number,
+                                  PayloadType payload_type,
+                                  base::TimeDelta duration,
+                                  base::TimeDelta duration_uptime,
+                                  int64_t payload_size,
+                                  metrics::AttemptResult attempt_result,
+                                  ErrorCode internal_error_code) override {}
+
+  void ReportUpdateAttemptDownloadMetrics(
+      int64_t payload_bytes_downloaded,
+      int64_t payload_download_speed_bps,
+      DownloadSource download_source,
+      metrics::DownloadErrorCode payload_download_error_code,
+      metrics::ConnectionType connection_type) override {}
+
+  void ReportAbnormallyTerminatedUpdateAttemptMetrics() override {}
+
+  void ReportSuccessfulUpdateMetrics(
+      int attempt_count,
+      int updates_abandoned_count,
+      PayloadType payload_type,
+      int64_t payload_size,
+      int64_t num_bytes_downloaded[kNumDownloadSources],
+      int download_overhead_percentage,
+      base::TimeDelta total_duration,
+      base::TimeDelta total_duration_uptime,
+      int reboot_count,
+      int url_switch_count) override {}
+
+  void ReportCertificateCheckMetrics(ServerToCheck server_to_check,
+                                     CertificateCheckResult result) override {}
+
+  void ReportFailedUpdateCount(int target_attempt) override {}
+
+  void ReportTimeToReboot(int time_to_reboot_minutes) override {}
+
+  void ReportInstallDateProvisioningSource(int source, int max) override {}
+
+  void ReportInternalErrorCode(ErrorCode error_code) override {}
+
+  void ReportKeyVersionMetrics(int kernel_min_version,
+                               int kernel_max_rollforward_version,
+                               bool kernel_max_rollforward_success) override {}
+
+  void ReportEnterpriseUpdateSeenToDownloadDays(
+      bool has_time_restriction_policy, int time_to_update_days) override {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MetricsReporterStub);
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_METRICS_REPORTER_STUB_H_
diff --git a/common/mock_download_action.h b/common/mock_download_action.h
new file mode 100644
index 0000000..ecda9a3
--- /dev/null
+++ b/common/mock_download_action.h
@@ -0,0 +1,41 @@
+//
+// Copyright (C) 2015 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_MOCK_DOWNLOAD_ACTION_H_
+#define UPDATE_ENGINE_COMMON_MOCK_DOWNLOAD_ACTION_H_
+
+#include <stdint.h>
+
+#include <gmock/gmock.h>
+
+#include "update_engine/common/download_action.h"
+#include "update_engine/common/error_code.h"
+
+namespace chromeos_update_engine {
+
+class MockDownloadActionDelegate : public DownloadActionDelegate {
+ public:
+  MOCK_METHOD3(BytesReceived,
+               void(uint64_t bytes_progressed,
+                    uint64_t bytes_received,
+                    uint64_t total));
+  MOCK_METHOD1(ShouldCancel, bool(ErrorCode* cancel_reason));
+  MOCK_METHOD0(DownloadComplete, void());
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_MOCK_DOWNLOAD_ACTION_H_
diff --git a/common/mock_excluder.h b/common/mock_excluder.h
index bc54772..560ba0d 100644
--- a/common/mock_excluder.h
+++ b/common/mock_excluder.h
@@ -14,8 +14,8 @@
 // limitations under the License.
 //
 
-#ifndef UPDATE_ENGINE_MOCK_APP_EXCLUDER_H_
-#define UPDATE_ENGINE_MOCK_APP_EXCLUDER_H_
+#ifndef UPDATE_ENGINE_COMMON_MOCK_APP_EXCLUDER_H_
+#define UPDATE_ENGINE_COMMON_MOCK_APP_EXCLUDER_H_
 
 #include "update_engine/common/excluder_interface.h"
 
@@ -34,4 +34,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // UPDATE_ENGINE_MOCK_APP_EXCLUDER_H_
+#endif  // UPDATE_ENGINE_COMMON_MOCK_APP_EXCLUDER_H_
diff --git a/common/mock_metrics_reporter.h b/common/mock_metrics_reporter.h
new file mode 100644
index 0000000..922d1ee
--- /dev/null
+++ b/common/mock_metrics_reporter.h
@@ -0,0 +1,99 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_MOCK_METRICS_REPORTER_H_
+#define UPDATE_ENGINE_COMMON_MOCK_METRICS_REPORTER_H_
+
+#include <string>
+
+#include <gmock/gmock.h>
+
+#include "update_engine/common/metrics_reporter_interface.h"
+
+namespace chromeos_update_engine {
+
+class MockMetricsReporter : public MetricsReporterInterface {
+ public:
+  MOCK_METHOD0(Initialize, void());
+
+  MOCK_METHOD1(ReportRollbackMetrics, void(metrics::RollbackResult result));
+
+  MOCK_METHOD2(ReportEnterpriseRollbackMetrics,
+               void(bool success, const std::string& rollback_version));
+
+  MOCK_METHOD1(ReportDailyMetrics, void(base::TimeDelta os_age));
+
+  MOCK_METHOD4(ReportUpdateCheckMetrics,
+               void(SystemState* system_state,
+                    metrics::CheckResult result,
+                    metrics::CheckReaction reaction,
+                    metrics::DownloadErrorCode download_error_code));
+
+  MOCK_METHOD8(ReportUpdateAttemptMetrics,
+               void(SystemState* system_state,
+                    int attempt_number,
+                    PayloadType payload_type,
+                    base::TimeDelta duration,
+                    base::TimeDelta duration_uptime,
+                    int64_t payload_size,
+                    metrics::AttemptResult attempt_result,
+                    ErrorCode internal_error_code));
+
+  MOCK_METHOD5(ReportUpdateAttemptDownloadMetrics,
+               void(int64_t payload_bytes_downloaded,
+                    int64_t payload_download_speed_bps,
+                    DownloadSource download_source,
+                    metrics::DownloadErrorCode payload_download_error_code,
+                    metrics::ConnectionType connection_type));
+
+  MOCK_METHOD0(ReportAbnormallyTerminatedUpdateAttemptMetrics, void());
+
+  MOCK_METHOD10(ReportSuccessfulUpdateMetrics,
+                void(int attempt_count,
+                     int updates_abandoned_count,
+                     PayloadType payload_type,
+                     int64_t payload_size,
+                     int64_t num_bytes_downloaded[kNumDownloadSources],
+                     int download_overhead_percentage,
+                     base::TimeDelta total_duration,
+                     base::TimeDelta total_duration_uptime,
+                     int reboot_count,
+                     int url_switch_count));
+
+  MOCK_METHOD2(ReportCertificateCheckMetrics,
+               void(ServerToCheck server_to_check,
+                    CertificateCheckResult result));
+
+  MOCK_METHOD1(ReportFailedUpdateCount, void(int target_attempt));
+
+  MOCK_METHOD1(ReportTimeToReboot, void(int time_to_reboot_minutes));
+
+  MOCK_METHOD2(ReportInstallDateProvisioningSource, void(int source, int max));
+
+  MOCK_METHOD1(ReportInternalErrorCode, void(ErrorCode error_code));
+
+  MOCK_METHOD3(ReportKeyVersionMetrics,
+               void(int kernel_min_version,
+                    int kernel_max_rollforward_version,
+                    bool kernel_max_rollforward_success));
+
+  MOCK_METHOD2(ReportEnterpriseUpdateSeenToDownloadDays,
+               void(bool has_time_restriction_policy, int time_to_update_days));
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_MOCK_METRICS_REPORTER_H_
diff --git a/common/mock_service_observer.h b/common/mock_service_observer.h
new file mode 100644
index 0000000..2c895f9
--- /dev/null
+++ b/common/mock_service_observer.h
@@ -0,0 +1,35 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_MOCK_SERVICE_OBSERVER_H_
+#define UPDATE_ENGINE_COMMON_MOCK_SERVICE_OBSERVER_H_
+
+#include <gmock/gmock.h>
+#include "update_engine/common/service_observer_interface.h"
+
+namespace chromeos_update_engine {
+
+class MockServiceObserver : public ServiceObserverInterface {
+ public:
+  MOCK_METHOD1(
+      SendStatusUpdate,
+      void(const update_engine::UpdateEngineStatus& update_engine_status));
+  MOCK_METHOD1(SendPayloadApplicationComplete, void(ErrorCode error_code));
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_MOCK_SERVICE_OBSERVER_H_
diff --git a/common/network_selector.h b/common/network_selector.h
new file mode 100644
index 0000000..bfc09c5
--- /dev/null
+++ b/common/network_selector.h
@@ -0,0 +1,33 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_H_
+#define UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_H_
+
+#include <memory>
+
+#include "update_engine/common/network_selector_interface.h"
+
+namespace chromeos_update_engine {
+namespace network {
+
+// Creates the NetworkSelectorInterface instance for the given platform.
+std::unique_ptr<NetworkSelectorInterface> CreateNetworkSelector();
+
+}  // namespace network
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_H_
diff --git a/common/network_selector_interface.h b/common/network_selector_interface.h
new file mode 100644
index 0000000..42ce32e
--- /dev/null
+++ b/common/network_selector_interface.h
@@ -0,0 +1,48 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_INTERFACE_H_
+#define UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_INTERFACE_H_
+
+#include <cstdint>
+
+namespace chromeos_update_engine {
+
+typedef uint64_t NetworkId;
+
+// A constant value used to indicate the default network id. Defined in the
+// network_selector_*.cc file.
+extern const NetworkId kDefaultNetworkId;
+
+// A class that handles the network used for the connections performed from this
+// process in a platform-specific way.
+
+class NetworkSelectorInterface {
+ public:
+  virtual ~NetworkSelectorInterface() = default;
+
+  // Set the current process network. All sockets created in the future will be
+  // bound to this particular network. Call this with the special value
+  // kNetworkId to use the default network.
+  virtual bool SetProcessNetwork(NetworkId network_id) = 0;
+
+ protected:
+  NetworkSelectorInterface() = default;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_INTERFACE_H_
diff --git a/common/network_selector_stub.cc b/common/network_selector_stub.cc
new file mode 100644
index 0000000..24c0e25
--- /dev/null
+++ b/common/network_selector_stub.cc
@@ -0,0 +1,45 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "update_engine/common/network_selector_stub.h"
+
+#include <memory>
+
+#include <base/logging.h>
+
+namespace chromeos_update_engine {
+
+namespace network {
+
+// Factory defined in common/network_selector.h.
+std::unique_ptr<NetworkSelectorInterface> CreateNetworkSelector() {
+  return std::make_unique<NetworkSelectorStub>();
+}
+
+}  // namespace network
+
+// Defined in common/network_selector_interface.h.
+const NetworkId kDefaultNetworkId = 0;
+
+bool NetworkSelectorStub::SetProcessNetwork(NetworkId network_id) {
+  if (network_id != kDefaultNetworkId) {
+    LOG(ERROR) << "SetProcessNetwork not implemented.";
+    return false;
+  }
+  return true;
+}
+
+}  // namespace chromeos_update_engine
diff --git a/common/network_selector_stub.h b/common/network_selector_stub.h
new file mode 100644
index 0000000..b32df91
--- /dev/null
+++ b/common/network_selector_stub.h
@@ -0,0 +1,40 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_STUB_H_
+#define UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_STUB_H_
+
+#include <base/macros.h>
+
+#include "update_engine/common/network_selector_interface.h"
+
+namespace chromeos_update_engine {
+
+class NetworkSelectorStub final : public NetworkSelectorInterface {
+ public:
+  NetworkSelectorStub() = default;
+  ~NetworkSelectorStub() override = default;
+
+  // NetworkSelectorInterface overrides.
+  bool SetProcessNetwork(NetworkId network_id) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NetworkSelectorStub);
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_NETWORK_SELECTOR_STUB_H_
diff --git a/common/platform_constants_android.cc b/common/platform_constants_android.cc
deleted file mode 100644
index f468c3b..0000000
--- a/common/platform_constants_android.cc
+++ /dev/null
@@ -1,38 +0,0 @@
-//
-// Copyright (C) 2015 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-
-#include "update_engine/common/platform_constants.h"
-
-namespace chromeos_update_engine {
-namespace constants {
-
-const char kOmahaDefaultProductionURL[] =
-    "https://clients2.google.com/service/update2/brillo";
-const char kOmahaDefaultAUTestURL[] =
-    "https://clients2.google.com/service/update2/brillo";
-const char kOmahaUpdaterID[] = "Brillo";
-const char kOmahaPlatformName[] = "Brillo";
-const char kUpdatePayloadPublicKeyPath[] = "";
-const char kUpdateCertificatesPath[] = "/system/etc/security/otacerts.zip";
-const char kCACertificatesPath[] = "/system/etc/security/cacerts_google";
-// No deadline file API support on Android.
-const char kOmahaResponseDeadlineFile[] = "";
-const char kNonVolatileDirectory[] = "/data/misc/update_engine";
-const char kPostinstallMountOptions[] =
-    "context=u:object_r:postinstall_file:s0";
-
-}  // namespace constants
-}  // namespace chromeos_update_engine
diff --git a/common/platform_constants_chromeos.cc b/common/platform_constants_chromeos.cc
deleted file mode 100644
index fe94a45..0000000
--- a/common/platform_constants_chromeos.cc
+++ /dev/null
@@ -1,38 +0,0 @@
-//
-// Copyright (C) 2015 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-
-#include "update_engine/common/platform_constants.h"
-
-namespace chromeos_update_engine {
-namespace constants {
-
-const char kOmahaDefaultProductionURL[] =
-    "https://tools.google.com/service/update2";
-const char kOmahaDefaultAUTestURL[] =
-    "https://omaha-qa.sandbox.google.com/service/update2";
-const char kOmahaUpdaterID[] = "ChromeOSUpdateEngine";
-const char kOmahaPlatformName[] = "Chrome OS";
-const char kUpdatePayloadPublicKeyPath[] =
-    "/usr/share/update_engine/update-payload-key.pub.pem";
-const char kUpdateCertificatesPath[] = "";
-const char kCACertificatesPath[] = "/usr/share/chromeos-ca-certificates";
-const char kOmahaResponseDeadlineFile[] = "/tmp/update-check-response-deadline";
-// This directory is wiped during powerwash.
-const char kNonVolatileDirectory[] = "/var/lib/update_engine";
-const char kPostinstallMountOptions[] = "";
-
-}  // namespace constants
-}  // namespace chromeos_update_engine
diff --git a/common/service_observer_interface.h b/common/service_observer_interface.h
new file mode 100644
index 0000000..c471231
--- /dev/null
+++ b/common/service_observer_interface.h
@@ -0,0 +1,46 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_SERVICE_OBSERVER_INTERFACE_H_
+#define UPDATE_ENGINE_COMMON_SERVICE_OBSERVER_INTERFACE_H_
+
+#include <memory>
+#include <string>
+
+#include "update_engine/client_library/include/update_engine/update_status.h"
+#include "update_engine/common/error_code.h"
+
+namespace chromeos_update_engine {
+
+class ServiceObserverInterface {
+ public:
+  virtual ~ServiceObserverInterface() = default;
+
+  // Called whenever the value of these parameters changes. For |progress|
+  // value changes, this method will be called only if it changes significantly.
+  virtual void SendStatusUpdate(
+      const update_engine::UpdateEngineStatus& update_engine_status) = 0;
+
+  // Called whenever an update attempt is completed.
+  virtual void SendPayloadApplicationComplete(ErrorCode error_code) = 0;
+
+ protected:
+  ServiceObserverInterface() = default;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_SERVICE_OBSERVER_INTERFACE_H_
diff --git a/common/system_state.h b/common/system_state.h
new file mode 100644
index 0000000..7a67046
--- /dev/null
+++ b/common/system_state.h
@@ -0,0 +1,120 @@
+//
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_SYSTEM_STATE_H_
+#define UPDATE_ENGINE_COMMON_SYSTEM_STATE_H_
+
+namespace chromeos_update_manager {
+
+class UpdateManager;
+
+}  // namespace chromeos_update_manager
+
+namespace policy {
+
+class DevicePolicy;
+
+}  // namespace policy
+
+namespace chromeos_update_engine {
+
+// SystemState is the root class within the update engine. So we should avoid
+// any circular references in header file inclusion. Hence forward-declaring
+// the required classes.
+class BootControlInterface;
+class ClockInterface;
+class ConnectionManagerInterface;
+class DlcServiceInterface;
+class HardwareInterface;
+class MetricsReporterInterface;
+class OmahaRequestParams;
+class P2PManager;
+class PayloadStateInterface;
+class PowerManagerInterface;
+class PrefsInterface;
+class UpdateAttempter;
+
+// An interface to global system context, including platform resources,
+// the current state of the system, high-level objects whose lifetime is same
+// as main, system interfaces, etc.
+// Carved out separately so it can be mocked for unit tests.
+// Currently it has only one method, but we should start migrating other
+// methods to use this as and when needed to unit test them.
+// TODO(jaysri): Consider renaming this to something like GlobalContext.
+class SystemState {
+ public:
+  // Destructs this object.
+  virtual ~SystemState() {}
+
+  // Sets or gets the latest device policy.
+  virtual void set_device_policy(const policy::DevicePolicy* device_policy) = 0;
+  virtual const policy::DevicePolicy* device_policy() = 0;
+
+  // Gets the interface object for the bootloader control interface.
+  virtual BootControlInterface* boot_control() = 0;
+
+  // Gets the interface object for the clock.
+  virtual ClockInterface* clock() = 0;
+
+  // Gets the connection manager object.
+  virtual ConnectionManagerInterface* connection_manager() = 0;
+
+  // Gets the hardware interface object.
+  virtual HardwareInterface* hardware() = 0;
+
+  // Gets the Metrics Library interface for reporting UMA stats.
+  virtual MetricsReporterInterface* metrics_reporter() = 0;
+
+  // Gets the interface object for persisted store.
+  virtual PrefsInterface* prefs() = 0;
+
+  // Gets the interface object for the persisted store that persists across
+  // powerwashes. Please note that this should be used very seldomly and must
+  // be forwards and backwards compatible as powerwash is used to go back and
+  // forth in system versions.
+  virtual PrefsInterface* powerwash_safe_prefs() = 0;
+
+  // Gets the interface for the payload state object.
+  virtual PayloadStateInterface* payload_state() = 0;
+
+  // Returns a pointer to the update attempter object.
+  virtual UpdateAttempter* update_attempter() = 0;
+
+  // Returns a pointer to the object that stores the parameters that are
+  // common to all Omaha requests.
+  virtual OmahaRequestParams* request_params() = 0;
+
+  // Returns a pointer to the P2PManager singleton.
+  virtual P2PManager* p2p_manager() = 0;
+
+  // Returns a pointer to the UpdateManager singleton.
+  virtual chromeos_update_manager::UpdateManager* update_manager() = 0;
+
+  // Gets the power manager object. Mocked during test.
+  virtual PowerManagerInterface* power_manager() = 0;
+
+  // If true, this is the first instance of the update engine since the system
+  // restarted. Important for tracking whether you are running instance of the
+  // update engine on first boot or due to a crash/restart.
+  virtual bool system_rebooted() = 0;
+
+  // Returns a pointer to the DlcServiceInterface singleton.
+  virtual DlcServiceInterface* dlcservice() = 0;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_SYSTEM_STATE_H_