gdata: Fix a crash at shutdown with pending gdata operations

chrome/browser/chromeos/system/ash_system_tray_delegate.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/system/ash_system_tray_delegate.h"
 
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/audio/audio_observer.h"
 #include "ash/system/bluetooth/bluetooth_observer.h"
@@ skipping 211 matching lines @@
     NetworkLibrary* crosnet = CrosLibrary::Get()->GetNetworkLibrary();
     if (crosnet) {
       crosnet->RemoveNetworkManagerObserver(this);
       crosnet->RemoveCellularDataPlanObserver(this);
     }
     input_method::InputMethodManager::GetInstance()->RemoveObserver(this);
     system::TimezoneSettings::GetInstance()->RemoveObserver(this);
     if (SystemKeyEventListener::GetInstance())
       SystemKeyEventListener::GetInstance()->RemoveCapsLockObserver(this);
     bluetooth_adapter_->RemoveObserver(this);
+
+    // Stop observing gdata operations.
+    Profile* profile = ProfileManager::GetDefaultProfile();
+    if (gdata::util::IsGDataAvailable(profile)) {
+      GDataSystemService* system_service =
+          GDataSystemServiceFactory::FindForProfile(profile);
+      if (system_service && system_service->file_system()) {
+        system_service->file_system()->GetOperationRegistry()->
+            RemoveObserver(this);
+      }
+    }
   }
 
   // Overridden from ash::SystemTrayDelegate:
   virtual bool GetTrayVisibilityOnStartup() OVERRIDE {
     return !chromeos::KioskModeSettings::Get()->IsKioskModeEnabled();
   }
 
   virtual const string16 GetUserDisplayName() const OVERRIDE {
     return UserManager::Get()->GetLoggedInUser().GetDisplayName();
   }
@@ skipping 982 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(SystemTrayDelegate);
 };
 
 }  // namespace
 
 ash::SystemTrayDelegate* CreateSystemTrayDelegate(ash::SystemTray* tray) {
   return new chromeos::SystemTrayDelegate(tray);
 }
 
 }  // namespace chromeos