gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/service/cmd_buffer_engine.h

 // Copyright (c) 2011 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.
 
 // This file defines the CommandBufferEngine class, providing the main loop for
 // the service, exposing the RPC API, managing the command parser.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_CMD_BUFFER_ENGINE_H_
 #define GPU_COMMAND_BUFFER_SERVICE_CMD_BUFFER_ENGINE_H_
 
@@ skipping 11 matching lines @@
   }
 
   // Gets the base address and size of a registered shared memory buffer.
   // Parameters:
   //   shm_id: the identifier for the shared memory buffer.
   virtual Buffer GetSharedMemoryBuffer(int32 shm_id) = 0;
 
   // Sets the token value.
   virtual void set_token(int32 token) = 0;
 
+  // Sets the async token value.
+  virtual void set_async_token(uint32 async_token) = 0;
+
   // Sets the shared memory buffer used for commands.
   virtual bool SetGetBuffer(int32 transfer_buffer_id) = 0;
 
   // Sets the "get" pointer. Return false if offset is out of range.
   virtual bool SetGetOffset(int32 offset) = 0;
 
   // Gets the "get" pointer.
   virtual int32 GetGetOffset() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CommandBufferEngine);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_CMD_BUFFER_ENGINE_H_