Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/chromeos/drive/drive_sync_client.cc

 // 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.
 
 #include "chrome/browser/chromeos/drive/drive_sync_client.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 412 matching lines @@
     DVLOG(1) << "Uploaded " << resource_id;
   } else {
     // TODO(satorux): We should re-queue if the error is recoverable.
     LOG(WARNING) << "Failed to upload " << resource_id << ": " << error;
   }
 
   // Continue the loop.
   DoSyncLoop();
 }
 
-void DriveSyncClient::Observe(int type,
-                              const content::NotificationSource& source,
-                              const content::NotificationDetails& details) {
+void DriveSyncClient::OnPreferenceChanged(PrefServiceBase* service,
+                                          const std::string& pref_name) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Resume the sync loop if gdata preferences are changed. Note that we
   // don't need to check the new values here as these will be checked in
   // ShouldStopSyncLoop() as soon as the loop is resumed.
   StartSyncLoop();
 }
 
 void DriveSyncClient::OnConnectionTypeChanged(
     net::NetworkChangeNotifier::ConnectionType type) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Resume the sync loop if the network is changed. Note that we don't need to
   // check the type of the network as it will be checked in ShouldStopSyncLoop()
   // as soon as the loop is resumed.
   StartSyncLoop();
 }
 
 }  // namespace drive