[Sync] Initial USS service implementation for DeviceInfo.

components/sync_driver/local_device_info_provider_mock.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/sync_driver/local_device_info_provider_mock.h"
 
 namespace sync_driver {
 
 LocalDeviceInfoProviderMock::LocalDeviceInfoProviderMock()
   : is_initialized_(false) {}
@@ skipping 28 matching lines @@
 
 std::string LocalDeviceInfoProviderMock::GetLocalSyncCacheGUID() const {
   return local_device_info_.get() ? local_device_info_->guid() : "";
 }
 
 void LocalDeviceInfoProviderMock::Initialize(
     const std::string& cache_guid, const std::string& signin_scoped_device_id) {
   // Ignored for the mock provider.
 }
 
+void LocalDeviceInfoProviderMock::Initialize(

[stanisc, 2015/10/22 20:16:53]

I am not sure why did you need to add this. You could still construct it in
advance with the needed data and call SetInitialized. That is what tests for
DeviceInfoSyncService do.

[skym, 2015/10/23 20:29:49]

Because then I cannot test all the cases. The way I see it, DeviceInfo's service
has 3 dependencies:

1) Provider
2) DataStore (right now this is directory, in the future it'll be a levelDB)
3) Processor

None of these are ready upon the service's construction, but once all three are
available, the service should compare the stored local device info to the
provider's device info, see if there is any discrepancy, and commit if needed.

The way we test to see if the provider has been initialized or not is by calling
GetLocalDeviceInfo(), and if it returns NULL, then the provider is not ready.
Without my change here, I'm forced to always start the provider as initialized,
regardless of if the initialized callback is going to get invoked or not. I'll
never be able to test the case where DataStore and Processor initialize before
the Provider.

+    scoped_ptr<DeviceInfo> local_device_info) {
+  local_device_info_.swap(local_device_info);
+  SetInitialized(true);
+}
+
 scoped_ptr<LocalDeviceInfoProvider::Subscription>
 LocalDeviceInfoProviderMock::RegisterOnInitializedCallback(
     const base::Closure& callback) {
   DCHECK(!is_initialized_);
   return callback_list_.Add(callback);
 }
 
 void LocalDeviceInfoProviderMock::SetInitialized(bool is_initialized) {
   is_initialized_ = is_initialized;
   if (is_initialized_) {
     callback_list_.Notify();
   }
 }
 
 }  // namespace sync_driver