gpu: Ensure that preempted channels wake up after preemption.

content/common/gpu/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 "content/common/gpu/gpu_channel.h"
 
 #include <utility>
 
 #if defined(OS_WIN)
 #include <windows.h>
@@ skipping 213 matching lines @@
     return nullptr;
   sync_point_order_data_->BeginProcessingOrderNumber(
       channel_messages_.front()->order_number);
   return channel_messages_.front().get();
 }
 
 void GpuChannelMessageQueue::PauseMessageProcessing() {
   base::AutoLock auto_lock(channel_lock_);
   DCHECK(!channel_messages_.empty());
 
+  // If we have been preempted by another channel, just post a task to wake up.
+  if (scheduled_)
+    channel_->PostHandleMessage(this);
+
   sync_point_order_data_->PauseProcessingOrderNumber(
       channel_messages_.front()->order_number);
 }
 
 void GpuChannelMessageQueue::FinishMessageProcessing() {
   base::AutoLock auto_lock(channel_lock_);
   DCHECK(!channel_messages_.empty());
   DCHECK(scheduled_);
 
   sync_point_order_data_->FinishProcessingOrderNumber(
@@ skipping 813 matching lines @@
     }
   }
 }
 
 void GpuChannel::HandleUpdateValueState(
     unsigned int target, const gpu::ValueState& state) {
   pending_valuebuffer_state_->UpdateState(target, state);
 }
 
 }  // namespace content