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

components/sync/user_events/user_event_service_impl.cc

Index: components/sync/user_events/user_event_service_impl.cc
diff --git a/components/sync/user_events/user_event_service.cc b/components/sync/user_events/user_event_service_impl.cc
similarity index 69%
copy from components/sync/user_events/user_event_service.cc
copy to components/sync/user_events/user_event_service_impl.cc
index 7a7e0b8cc58de5981de20c4ac054e3ff14475d9c..007c4da6fdae4a9a8eef3c01c433540f998c30fc 100644
--- a/components/sync/user_events/user_event_service.cc
+++ b/components/sync/user_events/user_event_service_impl.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/sync/user_events/user_event_service.h"
+#include "components/sync/user_events/user_event_service_impl.h"
 
 #include <utility>
 
@@ -19,19 +19,20 @@ using sync_pb::UserEventSpecifics;
 
 namespace syncer {
 
-UserEventService::UserEventService(SyncService* sync_service,
-                                   std::unique_ptr<UserEventSyncBridge> bridge)
+UserEventServiceImpl::UserEventServiceImpl(
+    SyncService* sync_service,
+    std::unique_ptr<UserEventSyncBridge> bridge)
     : sync_service_(sync_service),
       bridge_(std::move(bridge)),
       session_id_(base::RandUint64()) {
   // TODO(skym): Subscribe to events about field trial membership changing.
 }
 
-UserEventService::~UserEventService() {}
+UserEventServiceImpl::~UserEventServiceImpl() {}
 
-void UserEventService::Shutdown() {}
+void UserEventServiceImpl::Shutdown() {}
 
-void UserEventService::RecordUserEvent(
+void UserEventServiceImpl::RecordUserEvent(
     std::unique_ptr<UserEventSpecifics> specifics) {
   if (CanRecordEvent(*specifics)) {
     DCHECK(!specifics->has_session_id());
@@ -40,15 +41,16 @@ void UserEventService::RecordUserEvent(
   }
 }
 
-void UserEventService::RecordUserEvent(const UserEventSpecifics& specifics) {
+void UserEventServiceImpl::RecordUserEvent(
+    const UserEventSpecifics& specifics) {
   RecordUserEvent(base::MakeUnique<UserEventSpecifics>(specifics));
 }
 
-base::WeakPtr<ModelTypeSyncBridge> UserEventService::GetSyncBridge() {
+base::WeakPtr<ModelTypeSyncBridge> UserEventServiceImpl::GetSyncBridge() {
   return bridge_->AsWeakPtr();
 }
 
-bool UserEventService::CanRecordEvent(const UserEventSpecifics& specifics) {
+bool UserEventServiceImpl::CanRecordEvent(const UserEventSpecifics& specifics) {
   // We only record events if the user is syncing history and has not enabled
   // a custom passphrase. The type HISTORY_DELETE_DIRECTIVES is enabled in and
   // only in this exact scenario.
@@ -57,8 +59,9 @@ bool UserEventService::CanRecordEvent(const UserEventSpecifics& specifics) {
          sync_service_->GetPreferredDataTypes().Has(HISTORY_DELETE_DIRECTIVES);
 }
 
-void RegisterDependentFieldTrial(const std::string& trial_name,
-                                 UserEventSpecifics::EventCase event_case) {
+void UserEventServiceImpl::RegisterDependentFieldTrial(
+    const std::string& trial_name,
+    UserEventSpecifics::EventCase event_case) {
   // TODO(skym): Implementation.
 }