Add missing lock in RetireSyncPointOnGpuThread

gpu/command_buffer/service/in_process_command_buffer.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 "gpu/command_buffer/service/in_process_command_buffer.h"
 
 #include <queue>
 #include <set>
 #include <utility>
 
@@ skipping 680 matching lines @@
 
 void InProcessCommandBuffer::RetireSyncPoint(uint32 sync_point) {
   QueueTask(base::Bind(&InProcessCommandBuffer::RetireSyncPointOnGpuThread,
                        base::Unretained(this),
                        sync_point));
 }
 
 void InProcessCommandBuffer::RetireSyncPointOnGpuThread(uint32 sync_point) {
   gles2::MailboxManager* mailbox_manager =
       decoder_->GetContextGroup()->mailbox_manager();
-  if (mailbox_manager->UsesSync() && MakeCurrent())
-    mailbox_manager->PushTextureUpdates();
+  if (mailbox_manager->UsesSync()) {
+    bool make_current_success = false;
+    {
+      base::AutoLock lock(command_buffer_lock_);
+      make_current_success = MakeCurrent();
+    }
+    if (make_current_success)
+      mailbox_manager->PushTextureUpdates();
+  }
   g_sync_point_manager.Get().RetireSyncPoint(sync_point);
 }
 
 void InProcessCommandBuffer::SignalSyncPoint(unsigned sync_point,
                                              const base::Closure& callback) {
   CheckSequencedThread();
   QueueTask(base::Bind(&InProcessCommandBuffer::SignalSyncPointOnGpuThread,
                        base::Unretained(this),
                        sync_point,
                        WrapCallback(callback)));
@@ skipping 113 matching lines @@
 }
 #endif
 
 // static
 void InProcessCommandBuffer::SetGpuMemoryBufferFactory(
     InProcessGpuMemoryBufferFactory* factory) {
   g_gpu_memory_buffer_factory = factory;
 }
 
 }  // namespace gpu