gpu: Add GpuFence framework.

gpu/command_buffer/client/gpu_control.h

 // Copyright 2014 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_CLIENT_GPU_CONTROL_H_
 #define GPU_COMMAND_BUFFER_CLIENT_GPU_CONTROL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "gpu/command_buffer/common/capabilities.h"
 #include "gpu/command_buffer/common/command_buffer_id.h"
 #include "gpu/command_buffer/common/constants.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/gpu_export.h"
 
 extern "C" typedef struct _ClientBuffer* ClientBuffer;
+extern "C" typedef struct _ClientFence* ClientFence;
 
 namespace base {
 class Lock;
 }
 
 namespace gfx {
 class GpuMemoryBuffer;
 }
 
 namespace gpu {
@@ skipping 69 matching lines @@
   // Runs |callback| when sync token is signalled.
   virtual void SignalSyncToken(const SyncToken& sync_token,
                                const base::Closure& callback) = 0;
 
   // Under some circumstances a sync token may be used which has not been
   // verified to have been flushed. For example, fence syncs queued on the
   // same channel as the wait command guarantee that the fence sync will
   // be enqueued first so does not need to be flushed.
   virtual bool CanWaitUnverifiedSyncToken(const SyncToken* sync_token) = 0;
 
+  // Create a fence for a client fence. Returns its ID or -1 on error.
+  virtual int32_t CreateFence(ClientFence fence) = 0;
+
+  // Destroy a fence. The ID must be positive.
+  virtual void DestroyFence(int32_t id) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(GpuControl);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GPU_CONTROL_H_