[Sync] SyncEngine refactor part 1: interfaces.

components/browser_sync/profile_sync_service.cc

Index: components/browser_sync/profile_sync_service.cc
diff --git a/components/browser_sync/profile_sync_service.cc b/components/browser_sync/profile_sync_service.cc
index 7cbe502b1b599459b0288eef0e0728695f71332d..ce4d28fdef56b88c16cc5de887c6f1b4e09e271c 100644
--- a/components/browser_sync/profile_sync_service.cc
+++ b/components/browser_sync/profile_sync_service.cc
@@ -108,7 +108,7 @@ using syncer::ModelTypeChangeProcessor;
 using syncer::ModelTypeSet;
 using syncer::ModelTypeStore;
 using syncer::ProtocolEventObserver;
-using syncer::SyncBackendHost;
+using syncer::SyncEngine;
 using syncer::SyncCredentials;
 using syncer::SyncProtocolError;
 using syncer::WeakHandle;
@@ -536,11 +536,10 @@ void ProfileSyncService::InitializeBackend(bool delete_stale_data) {
       local_sync_backend_folder.Append(kLoopbackServerBackendFilename);
 #endif  // defined(OS_WIN)
 
-  SyncBackendHost::HttpPostProviderFactoryGetter
-      http_post_provider_factory_getter =
-          base::Bind(&syncer::NetworkResources::GetHttpPostProviderFactory,
-                     base::Unretained(network_resources_.get()),
-                     url_request_context_, network_time_update_callback_);
+  SyncEngine::HttpPostProviderFactoryGetter http_post_provider_factory_getter =
+      base::Bind(&syncer::NetworkResources::GetHttpPostProviderFactory,
+                 base::Unretained(network_resources_.get()),
+                 url_request_context_, network_time_update_callback_);
 
   backend_->Initialize(
       this, sync_thread_->task_runner(), GetJsEventHandler(), sync_service_url_,
@@ -621,14 +620,12 @@ void ProfileSyncService::StartUpSlowBackendComponents() {
   invalidation::InvalidationService* invalidator =
       sync_client_->GetInvalidationService();
 
-  backend_.reset(
-      sync_client_->GetSyncApiComponentFactory()->CreateSyncBackendHost(
-          debug_identifier_, invalidator, sync_prefs_.AsWeakPtr(),
-          directory_path_));
+  backend_.reset(sync_client_->GetSyncApiComponentFactory()->CreateSyncEngine(
+      debug_identifier_, invalidator, sync_prefs_.AsWeakPtr(),
+      directory_path_));
 
-  // Initialize the backend.  Every time we start up a new SyncBackendHost,
-  // we'll want to start from a fresh SyncDB, so delete any old one that might
-  // be there.
+  // Initialize the backend. Every time we start up a new SyncEngine, we'll want
+  // to start from a fresh SyncDB, so delete any old one that might be there.
   InitializeBackend(ShouldDeleteSyncFolder());
 
   UpdateFirstSyncTimePref();
@@ -788,7 +785,7 @@ void ProfileSyncService::ShutdownImpl(syncer::ShutdownReason reason) {
 
   // Move aside the backend so nobody else tries to use it while we are
   // shutting it down.
-  std::unique_ptr<SyncBackendHost> doomed_backend(backend_.release());
+  std::unique_ptr<SyncEngine> doomed_backend(backend_.release());
   if (doomed_backend) {
     doomed_backend->Shutdown(reason);
     doomed_backend.reset();
@@ -832,7 +829,7 @@ void ProfileSyncService::StopImpl(SyncStopDataFate data_fate) {
   switch (data_fate) {
     case KEEP_DATA:
       // TODO(maxbogue): Investigate whether this logic can/should be moved
-      // into ShutdownImpl or SyncBackendHost itself.
+      // into ShutdownImpl or SyncEngine itself.

[skym, 2016/12/02 20:54:54]

This is so ambiguous and confusing with this name. Are you advocating for moving
this logic into the SyncEngine facade? Or the interface? Or onto some logic
that's inside the "engine"?

[maxbogue, 2016/12/02 23:59:27]

Clarified it to "sync engine" (aka the last of the options you mentioned).

       if (HasSyncingBackend()) {
         backend_->UnregisterInvalidationIds();
       }
@@ -943,7 +940,7 @@ void ProfileSyncService::UpdateBackendInitUMA(bool success) {
 
   base::Time on_backend_initialized_time = base::Time::Now();
   base::TimeDelta delta =
-      on_backend_initialized_time - startup_controller_->start_backend_time();
+      on_backend_initialized_time - startup_controller_->start_engine_time();
   if (is_first_time_sync_configure_) {
     UMA_HISTOGRAM_LONG_TIMES("Sync.BackendInitializeFirstTime", delta);
   } else {
@@ -1475,20 +1472,19 @@ std::string ProfileSyncService::QuerySyncStatusSummaryString() {
 }
 
 std::string ProfileSyncService::GetBackendInitializationStateString() const {
-  return startup_controller_->GetBackendInitializationStateString();
+  return startup_controller_->GetEngineInitializationStateString();
 }
 
 bool ProfileSyncService::IsSetupInProgress() const {
   return startup_controller_->IsSetupInProgress();
 }
 
-bool ProfileSyncService::QueryDetailedSyncStatus(
-    SyncBackendHost::Status* result) {
+bool ProfileSyncService::QueryDetailedSyncStatus(SyncEngine::Status* result) {
   if (backend_.get() && backend_initialized_) {
     *result = backend_->GetDetailedStatus();
     return true;
   } else {
-    SyncBackendHost::Status status;
+    SyncEngine::Status status;
     status.sync_protocol_error = last_actionable_error_;
     *result = status;
     return false;
@@ -1866,7 +1862,7 @@ std::unique_ptr<base::Value> ProfileSyncService::GetTypeStatusMap() {
     }
   }
 
-  SyncBackendHost::Status detailed_status = backend_->GetDetailedStatus();
+  SyncEngine::Status detailed_status = backend_->GetDetailedStatus();
   ModelTypeSet& throttled_types(detailed_status.throttled_types);
   ModelTypeSet& backed_off_types(detailed_status.backed_off_types);
   ModelTypeSet registered = GetRegisteredDataTypes();