[Sync] Split UserEventService into interface and impl, add fake impl, add unit tests.

components/sync/user_events/user_event_service_impl.h

 // Copyright 2017 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.
 
-#ifndef COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SERVICE_H_
-#define COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SERVICE_H_
+#ifndef COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SERVICE_IMPL_H_
+#define COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SERVICE_IMPL_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/sync/protocol/user_event_specifics.pb.h"
+#include "components/sync/user_events/user_event_service.h"
 
 namespace syncer {
 
 class ModelTypeSyncBridge;
 class SyncService;
 class UserEventSyncBridge;
 
-class UserEventService : public KeyedService {
+class UserEventServiceImpl : public UserEventService {
  public:
-  UserEventService(SyncService* sync_service,
-                   std::unique_ptr<UserEventSyncBridge> bridge);
+  UserEventServiceImpl(SyncService* sync_service,
+                       std::unique_ptr<UserEventSyncBridge> bridge);
+  ~UserEventServiceImpl() override;
 
-  ~UserEventService() override;
-
-  // KeyedService implementation
+  // KeyedService implementation.
   void Shutdown() override;
 
-  // Records a given event to be reported. Relevant settings will be checked to
-  // verify user events should be emitted and this will no-op if the the
-  // requisite permissions are not present.
-  void RecordUserEvent(std::unique_ptr<sync_pb::UserEventSpecifics> specifics);
-  void RecordUserEvent(const sync_pb::UserEventSpecifics& specifics);
-
-  // Register that knowledge about a given field trial is important when
-  // interpreting specified user event type, and should be recorded if assigned.
+  // UserEventServiceImpl implementation.

[Patrick Noland, 2017/05/30 23:06:41]

I think you mean UserEventService implementation?

[skym, 2017/05/30 23:21:40]

Done.

+  void RecordUserEvent(
+      std::unique_ptr<sync_pb::UserEventSpecifics> specifics) override;
+  void RecordUserEvent(const sync_pb::UserEventSpecifics& specifics) override;
   void RegisterDependentFieldTrial(
       const std::string& trial_name,
-      sync_pb::UserEventSpecifics::EventCase event_case);
-
-  base::WeakPtr<ModelTypeSyncBridge> GetSyncBridge();
+      sync_pb::UserEventSpecifics::EventCase event_case) override;
+  base::WeakPtr<ModelTypeSyncBridge> GetSyncBridge() override;
 
  private:
+  // Whether the given event should be recorded.

[Patrick Noland, 2017/05/30 23:06:41]

This comment is confusing when compared to the name of the function(can vs
should). Can you remove it and re-name the function? Assuming that the correct
word is "should."

[skym, 2017/05/30 23:21:39]

You're right, I'm using can and should synonymously, should is probably more
apt. Once we add sampling, this might change. I can remove the comment and
rename the method though.

   bool CanRecordEvent(const sync_pb::UserEventSpecifics& specifics);
 
   SyncService* sync_service_;
 
   std::unique_ptr<UserEventSyncBridge> bridge_;
 
   // Holds onto a random number for the duration of this execution of chrome. On
   // restart it will be regenerated. This can be attached to events to know
   // which events came from the same session.
   uint64_t session_id_;
 
-  DISALLOW_COPY_AND_ASSIGN(UserEventService);
+  DISALLOW_COPY_AND_ASSIGN(UserEventServiceImpl);
 };
 
 }  // namespace syncer
 
-#endif  // COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SERVICE_H_
+#endif  // COMPONENTS_SYNC_USER_EVENTS_USER_EVENT_SERVICE_IMPL_H_