gpu: Early return GpuCommandBufferStub::OnWaitSyncPoint() if the sync point is retired.

content/common/gpu/sync_point_manager.h

 // 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.
 
 #ifndef CONTENT_COMMON_GPU_SYNC_POINT_MANAGER_H_
 #define CONTENT_COMMON_GPU_SYNC_POINT_MANAGER_H_
 
 #include <vector>
 
 #include "base/callback.h"
@@ skipping 17 matching lines @@
   // Retires a sync point. This will call all the registered callbacks for this
   // sync point. This can only be called on the main thread.
   void RetireSyncPoint(uint32 sync_point);
 
   // Adds a callback to the sync point. The callback will be called when the
   // sync point is retired, or immediately (from within that function) if the
   // sync point was already retired (or not created yet). This can only be
   // called on the main thread.
   void AddSyncPointCallback(uint32 sync_point, const base::Closure& callback);
 
+  bool IsSyncPointRetired(uint32 sync_point);
+
  private:
   friend class base::RefCountedThreadSafe<SyncPointManager>;
   typedef std::vector<base::Closure> ClosureList;
   typedef base::hash_map<uint32, ClosureList > SyncPointMap;
 
   ~SyncPointManager();
 
   base::ThreadChecker thread_checker_;
 
   // Protects the 2 fields below. Note: callbacks shouldn't be called with this
   // held.
   base::Lock lock_;
   SyncPointMap sync_point_map_;
   uint32 next_sync_point_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncPointManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_SYNC_POINT_MANAGER_H_