Add DBus hiding client library

This library hides update_engine's legacy DBus dependencies until we
can remove them completely.

Bug: 24547247
Test: mmm system/update_engine; emerge-panther update_engine

Change-Id: I7f87f2a7c31d0940c376ef43368e53b0f3bc3407
diff --git a/client_library/client_impl.cc b/client_library/client_impl.cc
new file mode 100644
index 0000000..84ca184
--- /dev/null
+++ b/client_library/client_impl.cc
@@ -0,0 +1,91 @@
+//
+// 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/client_library/client_impl.h"
+
+#include <dbus/bus.h>
+#include <update_engine/dbus-constants.h>
+
+#include "update_engine/update_status_utils.h"
+
+using chromeos_update_engine::StringToUpdateStatus;
+using dbus::Bus;
+using org::chromium::UpdateEngineInterfaceProxy;
+using std::string;
+
+namespace update_engine {
+namespace internal {
+
+UpdateEngineClientImpl::UpdateEngineClientImpl() {
+  Bus::Options options;
+  options.bus_type = Bus::SYSTEM;
+  scoped_refptr<Bus> bus{new Bus{options}};
+  proxy_.reset(new UpdateEngineInterfaceProxy{bus});
+}
+
+bool UpdateEngineClientImpl::AttemptUpdate(const string& in_app_version,
+                                           const string& in_omaha_url,
+                                           bool at_user_request) {
+  return proxy_->AttemptUpdateWithFlags(
+      in_app_version,
+      in_omaha_url,
+      (at_user_request) ? 0 : kAttemptUpdateFlagNonInteractive,
+      nullptr);
+}
+
+bool UpdateEngineClientImpl::GetStatus(int64_t* out_last_checked_time,
+                                       double* out_progress,
+                                       UpdateStatus* out_update_status,
+                                       string* out_new_version,
+                                       int64_t* out_new_size) {
+  string status_as_string;
+  const bool success = proxy_->GetStatus(
+      out_last_checked_time,
+      out_progress,
+      &status_as_string,
+      out_new_version,
+      out_new_size,
+      nullptr);
+  if (!success) {
+    return false;
+  }
+
+  return StringToUpdateStatus(status_as_string, out_update_status);
+}
+
+bool UpdateEngineClientImpl::SetTargetChannel(const string& in_target_channel) {
+  return proxy_->SetChannel(
+      in_target_channel,
+      true,
+      nullptr);
+}
+
+bool UpdateEngineClientImpl::GetTargetChannel(string* out_channel) {
+  return proxy_->GetChannel(
+      false,  // Get the target channel.
+      out_channel,
+      nullptr);
+}
+
+bool UpdateEngineClientImpl::GetChannel(string* out_channel) {
+  return proxy_->GetChannel(
+      true,  // Get the current channel.
+      out_channel,
+      nullptr);
+}
+
+}  // namespace internal
+}  // namespace update_engine