[SyncFS] Make ExtensionService usage of SyncWorker asynchronous

chrome/browser/sync_file_system/drive_backend/sync_worker.h

Index: chrome/browser/sync_file_system/drive_backend/sync_worker.h
diff --git a/chrome/browser/sync_file_system/drive_backend/sync_worker.h b/chrome/browser/sync_file_system/drive_backend/sync_worker.h
index 752cfc603ac3995e3751278d3cabe06a54ec4692..e063a3ab10e727529019dd4bb6f09a7e18647012 100644
--- a/chrome/browser/sync_file_system/drive_backend/sync_worker.h
+++ b/chrome/browser/sync_file_system/drive_backend/sync_worker.h
@@ -67,7 +67,7 @@ class SyncWorker : public SyncTaskManager::Client {
   static scoped_ptr<SyncWorker> CreateOnWorker(
       const base::FilePath& base_dir,
       Observer* observer,
-      ExtensionServiceInterface* extension_service,
+      const base::WeakPtr<ExtensionServiceInterface>& extension_service,
       scoped_ptr<SyncEngineContext> sync_engine_context,
       leveldb::Env* env_override);
 
@@ -129,8 +129,16 @@ class SyncWorker : public SyncTaskManager::Client {
   friend class DriveBackendSyncTest;
   friend class SyncEngineTest;
 
+  enum AppStatus {

[peria, 2014/04/24 02:38:21]

(optional) I recommend to move this enum to extensin_service_interface.h

[tzik, 2014/04/24 06:56:55]

ExtensionRegistry has similar but fine grained, which is not needed for us.
So, I think its owners don't want to put this in.

+    APP_STATUS_ENABLED,
+    APP_STATUS_DISABLED,
+    APP_STATUS_UNINSTALLED,
+  };
+
+  typedef base::hash_map<std::string, AppStatus> AppStatusMap;
+
   SyncWorker(const base::FilePath& base_dir,
-             ExtensionServiceInterface* extension_service,
+             const base::WeakPtr<ExtensionServiceInterface>& extension_service,
              scoped_ptr<SyncEngineContext> sync_engine_context,
              leveldb::Env* env_override);
 
@@ -143,6 +151,12 @@ class SyncWorker : public SyncTaskManager::Client {
   void DidInitialize(SyncEngineInitializer* initializer,
                      SyncStatusCode status);
   void UpdateRegisteredApp();
+  static void QueryAppStatusOnUIThread(
+      const base::WeakPtr<ExtensionServiceInterface>& extension_service_ptr,
+      const std::vector<std::string>* apps,
+      AppStatusMap* status,
+      const base::Closure& callback);
+  void DidQueryAppStatus(const AppStatusMap* app_status);
   void DidProcessRemoteChange(RemoteToLocalSyncer* syncer,
                               const SyncFileCallback& callback,
                               SyncStatusCode status);
@@ -178,9 +192,7 @@ class SyncWorker : public SyncTaskManager::Client {
 
   scoped_ptr<SyncTaskManager> task_manager_;
 
-  // TODO(tzik): Add a proxy class for ExtensionServiceInterface to cross
-  // thread, and hold its instance as WeakPtr here.
-  ExtensionServiceInterface* extension_service_;
+  base::WeakPtr<ExtensionServiceInterface> extension_service_;
 
   scoped_ptr<SyncEngineContext> context_;
   ObserverList<Observer> observers_;