Add gpu::MailboxHolder to hold state for a gpu::Mailbox

cc/resources/texture_mailbox_deleter.cc

 // Copyright 2013 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 "cc/resources/texture_mailbox_deleter.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "cc/output/context_provider.h"
 #include "cc/resources/single_release_callback.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 
 namespace cc {
 
 static void DeleteTextureOnImplThread(
     const scoped_refptr<ContextProvider>& context_provider,
     unsigned texture_id,
-    unsigned sync_point,
+    uint32 sync_point,
     bool is_lost) {
   if (sync_point)
     context_provider->ContextGL()->WaitSyncPointCHROMIUM(sync_point);
   context_provider->ContextGL()->DeleteTextures(1, &texture_id);
 }
 
 static void PostTaskFromMainToImplThread(
     scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
     ReleaseCallback run_impl_callback,
     unsigned sync_point,
@@ skipping 52 matching lines @@
       impl_callbacks_.erase(impl_callbacks_.begin() + i);
       return;
     }
   }
 
   NOTREACHED() << "The Callback returned by GetDeleteCallback() was called "
                << "more than once.";
 }
 
 }  // namespace cc