diff --git a/mock_file_writer.h b/mock_file_writer.h
index 72d6a86..26cd45d 100644
--- a/mock_file_writer.h
+++ b/mock_file_writer.h
@@ -24,7 +24,8 @@
 
 class MockFileWriter : public FileWriter {
  public:
-  MOCK_METHOD2(Write, ssize_t(const void* bytes, size_t count));
+  MOCK_METHOD2(Write, bool(const void* bytes, size_t count));
+  MOCK_METHOD3(Write, bool(const void* bytes, size_t count, ErrorCode* error));
   MOCK_METHOD0(Close, int());
 };
 
diff --git a/mock_service_observer.h b/mock_service_observer.h
new file mode 100644
index 0000000..032f55a
--- /dev/null
+++ b/mock_service_observer.h
@@ -0,0 +1,38 @@
+//
+// 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_MOCK_SERVICE_OBSERVER_H_
+#define UPDATE_ENGINE_MOCK_SERVICE_OBSERVER_H_
+
+#include <gmock/gmock.h>
+#include "update_engine/service_observer_interface.h"
+
+namespace chromeos_update_engine {
+
+class MockServiceObserver : public ServiceObserverInterface {
+ public:
+  MOCK_METHOD5(SendStatusUpdate,
+               void(int64_t last_checked_time,
+                    double progress,
+                    update_engine::UpdateStatus status,
+                    const std::string& new_version,
+                    int64_t new_size));
+  MOCK_METHOD1(SendPayloadApplicationComplete, void(ErrorCode error_code));
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_MOCK_SERVICE_OBSERVER_H_
diff --git a/payload_consumer/download_action.cc b/payload_consumer/download_action.cc
index c3a5016..cd25962 100644
--- a/payload_consumer/download_action.cc
+++ b/payload_consumer/download_action.cc
@@ -173,6 +173,7 @@
   install_plan_.Dump();
 
   bytes_received_ = 0;
+  bytes_received_previous_payloads_ = 0;
   bytes_total_ = 0;
   for (const auto& payload : install_plan_.payloads)
     bytes_total_ += payload.size;
@@ -317,8 +318,10 @@
   }
 
   bytes_received_ += length;
+  uint64_t bytes_downloaded_total =
+      bytes_received_previous_payloads_ + bytes_received_;
   if (delegate_ && download_active_) {
-    delegate_->BytesReceived(length, bytes_received_, bytes_total_);
+    delegate_->BytesReceived(length, bytes_downloaded_total, bytes_total_);
   }
   if (writer_ && !writer_->Write(bytes, length, &code_)) {
     if (code_ != ErrorCode::kSuccess) {
@@ -349,13 +352,16 @@
 void DownloadAction::TransferComplete(HttpFetcher* fetcher, bool successful) {
   if (writer_) {
     LOG_IF(WARNING, writer_->Close() != 0) << "Error closing the writer.";
-    writer_ = nullptr;
+    if (delta_performer_.get() == writer_) {
+      // no delta_performer_ in tests, so leave the test writer in place
+      writer_ = nullptr;
+    }
   }
   download_active_ = false;
   ErrorCode code =
       successful ? ErrorCode::kSuccess : ErrorCode::kDownloadTransferError;
-  if (code == ErrorCode::kSuccess && delta_performer_.get()) {
-    if (!payload_->already_applied)
+  if (code == ErrorCode::kSuccess) {
+    if (delta_performer_ && !payload_->already_applied)
       code = delta_performer_->VerifyPayload(payload_->hash, payload_->size);
     if (code != ErrorCode::kSuccess) {
       LOG(ERROR) << "Download of " << install_plan_.download_url
@@ -365,10 +371,12 @@
         CloseP2PSharingFd(true);
     } else if (payload_ < &install_plan_.payloads.back() &&
                system_state_->payload_state()->NextPayload()) {
+      LOG(INFO) << "Incrementing to next payload";
       // No need to reset if this payload was already applied.
-      if (!payload_->already_applied)
+      if (delta_performer_ && !payload_->already_applied)
         DeltaPerformer::ResetUpdateProgress(prefs_, false);
       // Start downloading next payload.
+      bytes_received_previous_payloads_ += payload_->size;
       payload_++;
       install_plan_.download_url =
           system_state_->payload_state()->GetCurrentUrl();
diff --git a/payload_consumer/download_action.h b/payload_consumer/download_action.h
index d0e6000..786db20 100644
--- a/payload_consumer/download_action.h
+++ b/payload_consumer/download_action.h
@@ -166,7 +166,8 @@
 
   // For reporting status to outsiders
   DownloadActionDelegate* delegate_;
-  uint64_t bytes_received_{0};
+  uint64_t bytes_received_{0};  // per file/range
+  uint64_t bytes_received_previous_payloads_{0};
   uint64_t bytes_total_{0};
   bool download_active_{false};
 
diff --git a/payload_consumer/download_action_unittest.cc b/payload_consumer/download_action_unittest.cc
index 7d3ac6c..f42b1d8 100644
--- a/payload_consumer/download_action_unittest.cc
+++ b/payload_consumer/download_action_unittest.cc
@@ -41,6 +41,7 @@
 #include "update_engine/common/utils.h"
 #include "update_engine/fake_p2p_manager_configuration.h"
 #include "update_engine/fake_system_state.h"
+#include "update_engine/mock_file_writer.h"
 #include "update_engine/payload_consumer/mock_download_action.h"
 #include "update_engine/update_manager/fake_update_manager.h"
 
@@ -56,6 +57,7 @@
 using testing::AtLeast;
 using testing::InSequence;
 using testing::Return;
+using testing::SetArgPointee;
 using testing::_;
 
 class DownloadActionTest : public ::testing::Test { };
@@ -242,6 +244,92 @@
                false);  // use_download_delegate
 }
 
+TEST(DownloadActionTest, MultiPayloadProgressTest) {
+  std::vector<brillo::Blob> payload_datas;
+  // the first payload must be the largest, as it's the actual payload used by
+  // the MockHttpFetcher for all downloaded data.
+  payload_datas.emplace_back(4 * kMockHttpFetcherChunkSize + 256);
+  payload_datas.emplace_back(2 * kMockHttpFetcherChunkSize);
+  brillo::FakeMessageLoop loop(nullptr);
+  loop.SetAsCurrent();
+  FakeSystemState fake_system_state;
+  EXPECT_CALL(*fake_system_state.mock_payload_state(), NextPayload())
+      .WillOnce(Return(true));
+
+  MockFileWriter mock_file_writer;
+  EXPECT_CALL(mock_file_writer, Close()).WillRepeatedly(Return(0));
+  EXPECT_CALL(mock_file_writer, Write(_, _, _))
+      .WillRepeatedly(
+          DoAll(SetArgPointee<2>(ErrorCode::kSuccess), Return(true)));
+
+  InstallPlan install_plan;
+  uint64_t total_expected_download_size{0};
+  for (const auto& data : payload_datas) {
+    uint64_t size = data.size();
+    install_plan.payloads.push_back(
+        {.size = size, .type = InstallPayloadType::kFull});
+    total_expected_download_size += size;
+  }
+  ObjectFeederAction<InstallPlan> feeder_action;
+  feeder_action.set_obj(install_plan);
+  MockPrefs prefs;
+  MockHttpFetcher* http_fetcher = new MockHttpFetcher(
+      payload_datas[0].data(), payload_datas[0].size(), nullptr);
+  // takes ownership of passed in HttpFetcher
+  DownloadAction download_action(&prefs,
+                                 fake_system_state.boot_control(),
+                                 fake_system_state.hardware(),
+                                 &fake_system_state,
+                                 http_fetcher);
+  download_action.SetTestFileWriter(&mock_file_writer);
+  BondActions(&feeder_action, &download_action);
+  MockDownloadActionDelegate download_delegate;
+  {
+    InSequence s;
+    download_action.set_delegate(&download_delegate);
+    // these are hand-computed based on the payloads specified above
+    EXPECT_CALL(download_delegate,
+                BytesReceived(kMockHttpFetcherChunkSize,
+                              kMockHttpFetcherChunkSize,
+                              total_expected_download_size));
+    EXPECT_CALL(download_delegate,
+                BytesReceived(kMockHttpFetcherChunkSize,
+                              kMockHttpFetcherChunkSize * 2,
+                              total_expected_download_size));
+    EXPECT_CALL(download_delegate,
+                BytesReceived(kMockHttpFetcherChunkSize,
+                              kMockHttpFetcherChunkSize * 3,
+                              total_expected_download_size));
+    EXPECT_CALL(download_delegate,
+                BytesReceived(kMockHttpFetcherChunkSize,
+                              kMockHttpFetcherChunkSize * 4,
+                              total_expected_download_size));
+    EXPECT_CALL(download_delegate,
+                BytesReceived(256,
+                              kMockHttpFetcherChunkSize * 4 + 256,
+                              total_expected_download_size));
+    EXPECT_CALL(download_delegate,
+                BytesReceived(kMockHttpFetcherChunkSize,
+                              kMockHttpFetcherChunkSize * 5 + 256,
+                              total_expected_download_size));
+    EXPECT_CALL(download_delegate,
+                BytesReceived(kMockHttpFetcherChunkSize,
+                              total_expected_download_size,
+                              total_expected_download_size));
+  }
+  ActionProcessor processor;
+  processor.EnqueueAction(&feeder_action);
+  processor.EnqueueAction(&download_action);
+
+  loop.PostTask(
+      FROM_HERE,
+      base::Bind(
+          [](ActionProcessor* processor) { processor->StartProcessing(); },
+          base::Unretained(&processor)));
+  loop.Run();
+  EXPECT_FALSE(loop.PendingTasks());
+}
+
 namespace {
 class TerminateEarlyTestProcessorDelegate : public ActionProcessorDelegate {
  public:
diff --git a/update_attempter.h b/update_attempter.h
index b4e2f60..9dd844d 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -252,17 +252,20 @@
   FRIEND_TEST(UpdateAttempterTest, ActionCompletedDownloadTest);
   FRIEND_TEST(UpdateAttempterTest, ActionCompletedErrorTest);
   FRIEND_TEST(UpdateAttempterTest, ActionCompletedOmahaRequestTest);
+  FRIEND_TEST(UpdateAttempterTest, BootTimeInUpdateMarkerFile);
+  FRIEND_TEST(UpdateAttempterTest, BroadcastCompleteDownloadTest);
+  FRIEND_TEST(UpdateAttempterTest, ChangeToDownloadingOnReceivedBytesTest);
   FRIEND_TEST(UpdateAttempterTest, CreatePendingErrorEventTest);
   FRIEND_TEST(UpdateAttempterTest, CreatePendingErrorEventResumedTest);
   FRIEND_TEST(UpdateAttempterTest, DisableDeltaUpdateIfNeededTest);
+  FRIEND_TEST(UpdateAttempterTest, DownloadProgressAccumulationTest);
   FRIEND_TEST(UpdateAttempterTest, MarkDeltaUpdateFailureTest);
   FRIEND_TEST(UpdateAttempterTest, PingOmahaTest);
+  FRIEND_TEST(UpdateAttempterTest, ReportDailyMetrics);
   FRIEND_TEST(UpdateAttempterTest, ScheduleErrorEventActionNoEventTest);
   FRIEND_TEST(UpdateAttempterTest, ScheduleErrorEventActionTest);
-  FRIEND_TEST(UpdateAttempterTest, UpdateTest);
-  FRIEND_TEST(UpdateAttempterTest, ReportDailyMetrics);
-  FRIEND_TEST(UpdateAttempterTest, BootTimeInUpdateMarkerFile);
   FRIEND_TEST(UpdateAttempterTest, TargetVersionPrefixSetAndReset);
+  FRIEND_TEST(UpdateAttempterTest, UpdateTest);
 
   // CertificateChecker::Observer method.
   // Report metrics about the certificate being checked.
diff --git a/update_attempter_unittest.cc b/update_attempter_unittest.cc
index 4ebc85c..911f664 100644
--- a/update_attempter_unittest.cc
+++ b/update_attempter_unittest.cc
@@ -48,6 +48,7 @@
 #include "update_engine/fake_system_state.h"
 #include "update_engine/mock_p2p_manager.h"
 #include "update_engine/mock_payload_state.h"
+#include "update_engine/mock_service_observer.h"
 #include "update_engine/payload_consumer/filesystem_verifier_action.h"
 #include "update_engine/payload_consumer/install_plan.h"
 #include "update_engine/payload_consumer/payload_constants.h"
@@ -219,6 +220,7 @@
   EXPECT_CALL(*prefs_, GetInt64(kPrefsDeltaUpdateFailures, _)).Times(0);
   attempter_.ActionCompleted(nullptr, &action, ErrorCode::kSuccess);
   EXPECT_EQ(UpdateStatus::FINALIZING, attempter_.status());
+  EXPECT_EQ(0.0, attempter_.download_progress_);
   ASSERT_EQ(nullptr, attempter_.error_event_.get());
 }
 
@@ -232,6 +234,79 @@
   ASSERT_NE(nullptr, attempter_.error_event_.get());
 }
 
+TEST_F(UpdateAttempterTest, DownloadProgressAccumulationTest) {
+  // Simple test case, where all the values match (nothing was skipped)
+  uint64_t bytes_progressed_1 = 1024 * 1024;  // 1MB
+  uint64_t bytes_progressed_2 = 1024 * 1024;  // 1MB
+  uint64_t bytes_received_1 = bytes_progressed_1;
+  uint64_t bytes_received_2 = bytes_received_1 + bytes_progressed_2;
+  uint64_t bytes_total = 20 * 1024 * 1024;  // 20MB
+
+  double progress_1 =
+      static_cast<double>(bytes_received_1) / static_cast<double>(bytes_total);
+  double progress_2 =
+      static_cast<double>(bytes_received_2) / static_cast<double>(bytes_total);
+
+  EXPECT_EQ(0.0, attempter_.download_progress_);
+  // This is set via inspecting the InstallPlan payloads when the
+  // OmahaResponseAction is completed
+  attempter_.new_payload_size_ = bytes_total;
+  NiceMock<MockServiceObserver> observer;
+  EXPECT_CALL(observer,
+              SendStatusUpdate(
+                  _, progress_1, UpdateStatus::DOWNLOADING, _, bytes_total));
+  EXPECT_CALL(observer,
+              SendStatusUpdate(
+                  _, progress_2, UpdateStatus::DOWNLOADING, _, bytes_total));
+  attempter_.AddObserver(&observer);
+  attempter_.BytesReceived(bytes_progressed_1, bytes_received_1, bytes_total);
+  EXPECT_EQ(progress_1, attempter_.download_progress_);
+  // This iteration validates that a later set of updates to the variables are
+  // properly handled (so that |getStatus()| will return the same progress info
+  // as the callback is receiving.
+  attempter_.BytesReceived(bytes_progressed_2, bytes_received_2, bytes_total);
+  EXPECT_EQ(progress_2, attempter_.download_progress_);
+}
+
+TEST_F(UpdateAttempterTest, ChangeToDownloadingOnReceivedBytesTest) {
+  // The transition into UpdateStatus::DOWNLOADING happens when the
+  // first bytes are received.
+  uint64_t bytes_progressed = 1024 * 1024;    // 1MB
+  uint64_t bytes_received = 2 * 1024 * 1024;  // 2MB
+  uint64_t bytes_total = 20 * 1024 * 1024;    // 300MB
+  attempter_.status_ = UpdateStatus::CHECKING_FOR_UPDATE;
+  // This is set via inspecting the InstallPlan payloads when the
+  // OmahaResponseAction is completed
+  attempter_.new_payload_size_ = bytes_total;
+  EXPECT_EQ(0.0, attempter_.download_progress_);
+  NiceMock<MockServiceObserver> observer;
+  EXPECT_CALL(
+      observer,
+      SendStatusUpdate(_, _, UpdateStatus::DOWNLOADING, _, bytes_total));
+  attempter_.AddObserver(&observer);
+  attempter_.BytesReceived(bytes_progressed, bytes_received, bytes_total);
+  EXPECT_EQ(UpdateStatus::DOWNLOADING, attempter_.status_);
+}
+
+TEST_F(UpdateAttempterTest, BroadcastCompleteDownloadTest) {
+  // There is a special case to ensure that at 100% downloaded,
+  // download_progress_ is updated and that value broadcast. This test confirms
+  // that.
+  uint64_t bytes_progressed = 0;              // ignored
+  uint64_t bytes_received = 5 * 1024 * 1024;  // ignored
+  uint64_t bytes_total = 5 * 1024 * 1024;     // 300MB
+  attempter_.status_ = UpdateStatus::DOWNLOADING;
+  attempter_.new_payload_size_ = bytes_total;
+  EXPECT_EQ(0.0, attempter_.download_progress_);
+  NiceMock<MockServiceObserver> observer;
+  EXPECT_CALL(
+      observer,
+      SendStatusUpdate(_, 1.0, UpdateStatus::DOWNLOADING, _, bytes_total));
+  attempter_.AddObserver(&observer);
+  attempter_.BytesReceived(bytes_progressed, bytes_received, bytes_total);
+  EXPECT_EQ(1.0, attempter_.download_progress_);
+}
+
 TEST_F(UpdateAttempterTest, ActionCompletedOmahaRequestTest) {
   unique_ptr<MockHttpFetcher> fetcher(new MockHttpFetcher("", 0, nullptr));
   fetcher->FailTransfer(500);  // Sets the HTTP response code.