Use shared memory to update the renderer's view of the command buffer state.

gpu/command_buffer/service/command_buffer_service.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 GPU_COMMAND_BUFFER_SERVICE_COMMAND_BUFFER_SERVICE_H_
 #define GPU_COMMAND_BUFFER_SERVICE_COMMAND_BUFFER_SERVICE_H_
 
 #include <set>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "gpu/command_buffer/common/command_buffer.h"
+#include "gpu/command_buffer/common/command_buffer_shared.h"
 
 namespace gpu {
 
 // An object that implements a shared memory command buffer and a synchronous
 // API to manage the put and get pointers.
 class CommandBufferService : public CommandBuffer {
  public:
   typedef base::Callback<bool(int32)> GetBufferChangedCallback;
   CommandBufferService();
   virtual ~CommandBufferService();
@@ skipping 23 matching lines @@
   // This allows concurrency between the writer and the reader while giving the
   // writer a means of waiting for the reader to make some progress before
   // attempting to write more to the command buffer. Takes ownership of
   // callback.
   virtual void SetPutOffsetChangeCallback(const base::Closure& callback);
   // Sets a callback that is called whenever the get buffer is changed.
   virtual void SetGetBufferChangeCallback(
       const GetBufferChangedCallback& callback);
   virtual void SetParseErrorCallback(const base::Closure& callback);
 
+  // Setup the transfer buffer that shared state should be copied into.
+  void SetSharedStateBuffer(int32 transfer_buffer_id);
+
+  // Copy the current state into the shared state transfer buffer.
+  void UpdateState();
+
  private:
   int32 ring_buffer_id_;
   Buffer ring_buffer_;
+  CommandBufferSharedState* shared_state_;
   int32 num_entries_;
   int32 get_offset_;
   int32 put_offset_;
   base::Closure put_offset_change_callback_;
   GetBufferChangedCallback get_buffer_change_callback_;
   base::Closure parse_error_callback_;
   std::vector<Buffer> registered_objects_;
   std::set<int32> unused_registered_object_elements_;
   int32 token_;
   uint32 generation_;
   error::Error error_;
   error::ContextLostReason context_lost_reason_;
   size_t shared_memory_bytes_allocated_;
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_COMMAND_BUFFER_SERVICE_H_