DriveFileSyncService listens to OnAuthenticated event to recover from unavailable state

chrome/browser/sync_file_system/drive_file_sync_client.h

 // Copyright (c) 2012 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 CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_FILE_SYNC_CLIENT_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_FILE_SYNC_CLIENT_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
 #include "chrome/browser/google_apis/drive_service_interface.h"
 #include "chrome/browser/google_apis/drive_upload_error.h"
 #include "chrome/browser/google_apis/gdata_errorcode.h"
 #include "chrome/browser/google_apis/gdata_wapi_parser.h"
 
 class GURL;
 class Profile;
 
 namespace google_apis {
 class DriveUploaderInterface;
 }
 
 namespace sync_file_system {
 
+class DriveFileSyncClientObserver {
+ public:
+  DriveFileSyncClientObserver() {}
+  virtual ~DriveFileSyncClientObserver() {}
+  virtual void OnAuthenticated() = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DriveFileSyncClientObserver);
+};
+
 // This class is responsible for talking to the Drive service to get and put
 // Drive directories, files and metadata.
 // This class is owned by DriveFileSyncService.
-class DriveFileSyncClient : public base::NonThreadSafe,
+class DriveFileSyncClient : public google_apis::DriveServiceObserver,
+                            public base::NonThreadSafe,
                             public base::SupportsWeakPtr<DriveFileSyncClient> {
  public:
   typedef base::Callback<void(google_apis::GDataErrorCode error)>
       GDataErrorCallback;
   typedef base::Callback<void(google_apis::GDataErrorCode error,
                               const std::string& file_md5)>
       DownloadFileCallback;
   typedef base::Callback<void(google_apis::GDataErrorCode error,
                               const std::string& resource_id,
                               const std::string& file_md5)>
       UploadFileCallback;
   typedef base::Callback<void(google_apis::GDataErrorCode error,
                               const std::string& resource_id)>
       ResourceIdCallback;
   typedef base::Callback<void(google_apis::GDataErrorCode error,
                               int64 changestamp)> ChangeStampCallback;
   typedef base::Callback<void(google_apis::GDataErrorCode error,
                               scoped_ptr<google_apis::DocumentFeed> feed)>
       DocumentFeedCallback;
   typedef base::Callback<void(google_apis::GDataErrorCode error,
                               scoped_ptr<google_apis::DocumentEntry> entry)>
       DocumentEntryCallback;
 
   explicit DriveFileSyncClient(Profile* profile);
   virtual ~DriveFileSyncClient();
 
+  void AddObserver(DriveFileSyncClientObserver* observer);
+  void RemoveObserver(DriveFileSyncClientObserver* observer);
+
   static scoped_ptr<DriveFileSyncClient> CreateForTesting(
       Profile* profile,
       scoped_ptr<google_apis::DriveServiceInterface> drive_service,
       scoped_ptr<google_apis::DriveUploaderInterface> drive_uploader);
 
   // Fetches Resource ID of the directory where we should place all files to
   // sync.  Upon completion, invokes |callback|.
   // If the directory does not exist on the server this also creates
   // the directory.
   void GetDriveDirectoryForSyncRoot(const ResourceIdCallback& callback);
@@ skipping 70 matching lines @@
 
   // Deletes the file identified by |resource_id|.
   // |remote_file_md5| represents the expected hash value of the file to be
   // deleted from Drive. If |remote_file_md5| is different from the actual
   // value, cancels the deletion and invokes |callback| with
   // GDataErrorCode::HTTP_CONFLICT immediately.
   void DeleteFile(const std::string& resource_id,
                   const std::string& remote_file_md5,
                   const GDataErrorCallback& callback);
 
+  // DriveServiceObserver override.
+  virtual void OnReadyToPerformOperations() OVERRIDE;
+
  private:
   friend class DriveFileSyncClientTest;
   friend class DriveFileSyncServiceTest;
 
   // Constructor for test use.
   DriveFileSyncClient(
       Profile* profile,
       scoped_ptr<google_apis::DriveServiceInterface> drive_service,
       scoped_ptr<google_apis::DriveUploaderInterface> drive_uploader);
 
@@ skipping 68 matching lines @@
                           scoped_ptr<google_apis::DocumentEntry> entry);
 
   void DidDeleteFile(const GDataErrorCallback& callback,
                      google_apis::GDataErrorCode error);
 
   static std::string FormatTitleQuery(const std::string& title);
 
   scoped_ptr<google_apis::DriveServiceInterface> drive_service_;
   scoped_ptr<google_apis::DriveUploaderInterface> drive_uploader_;
 
+  ObserverList<DriveFileSyncClientObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(DriveFileSyncClient);
 };
 
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_FILE_SYNC_CLIENT_H_