[Sync] Remove unneeded 'using syncer::' lines and 'syncer::' scopings

sync/notifier/chrome_invalidation_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 "sync/notifier/chrome_invalidation_client.h"
 
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 33 matching lines @@
   DCHECK(CalledOnValidThread());
   push_client_->RemoveObserver(this);
   Stop();
   DCHECK(!listener_);
 }
 
 void ChromeInvalidationClient::Start(
     const std::string& client_id, const std::string& client_info,
     const std::string& state,
     const InvalidationVersionMap& initial_max_invalidation_versions,
-    const syncer::WeakHandle<InvalidationStateTracker>&
-        invalidation_state_tracker,
+    const WeakHandle<InvalidationStateTracker>& invalidation_state_tracker,
     Listener* listener) {
   DCHECK(CalledOnValidThread());
   Stop();
 
   chrome_system_resources_.set_platform(client_info);
   chrome_system_resources_.Start();
 
   // The Storage resource is implemented as a write-through cache.  We populate
   // it with the initial state on startup, so subsequent writes go to disk and
   // update the in-memory cache, while reads just return the cached state.
@@ skipping 264 matching lines @@
   EmitStateChange();
 }
 
 void ChromeInvalidationClient::OnIncomingNotification(
     const notifier::Notification& notification) {
   DCHECK(CalledOnValidThread());
   // Do nothing, since this is already handled by |invalidation_client_|.
 }
 
 }  // namespace syncer