gdata: Fix a crash at shutdown with pending gdata operations

chrome/browser/chromeos/system/ash_system_tray_delegate.cc

Index: chrome/browser/chromeos/system/ash_system_tray_delegate.cc
diff --git a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
index d5449c49c9ab5ebee0f9a3fd91b5e6ceb338f29d..b07b1edf7180750fb78ba34471b32a49e968662a 100644
--- a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
+++ b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
@@ -229,6 +229,17 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
     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: