Revert of [Reland 1] Pepper takes ownership of a mailbox before passing it to the texture layer.

gpu/ipc/service/gpu_channel.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 "gpu/ipc/service/gpu_channel.h"
 
 #include <utility>
 
 #if defined(OS_WIN)
 #include <windows.h>
@@ skipping 774 matching lines @@
   GpuCommandBufferStub* stub = stubs_.get(routing_id);
 
   DCHECK(!stub || stub->IsScheduled());
 
   DVLOG(1) << "received message @" << &msg << " on channel @" << this
            << " with type " << msg.type();
 
   HandleMessageHelper(msg);
 
   // If we get descheduled or yield while processing a message.
-  if (!message_queue->IsScheduled()) {
-    DCHECK((uint32_t)GpuCommandBufferMsg_AsyncFlush::ID == msg.type() ||
-           (uint32_t)GpuCommandBufferMsg_WaitSyncToken::ID == msg.type());
+  if (stub && stub->HasUnprocessedCommands()) {
+    DCHECK_EQ((uint32_t)GpuCommandBufferMsg_AsyncFlush::ID, msg.type());
     message_queue->PauseMessageProcessing();
   } else {
     message_queue->FinishMessageProcessing();
   }
 }
 
 void GpuChannel::HandleMessageHelper(const IPC::Message& msg) {
   int32_t routing_id = msg.routing_id();
 
   bool handled = false;
@@ skipping 242 matching lines @@
           ->CreateImageForGpuMemoryBuffer(handle,
                                           size,
                                           format,
                                           internalformat,
                                           client_id_);
     }
   }
 }
 
 }  // namespace gpu