Update from https://crrev.com/316786

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 <stdint.h>
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "gpu/command_buffer/common/capabilities.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/gpu_export.h"
 
 extern "C" typedef struct _ClientBuffer* ClientBuffer;
 
+namespace base {
+class Lock;
+}
+
 namespace gfx {
 class GpuMemoryBuffer;
 }
 
 namespace gpu {
 
 // Common interface for GpuControl implementations.
 class GPU_EXPORT GpuControl {
  public:
   GpuControl() {}
@@ skipping 38 matching lines @@
   // Runs |callback| when a query created via glCreateQueryEXT() has cleared
   // passed the glEndQueryEXT() point.
   virtual void SignalQuery(uint32_t query, const base::Closure& callback) = 0;
 
   virtual void SetSurfaceVisible(bool visible) = 0;
 
   // Attaches an external stream to the texture given by |texture_id| and
   // returns a stream identifier.
   virtual uint32_t CreateStreamTexture(uint32_t texture_id) = 0;
 
+  // Sets a lock this will be held on every callback from the GPU
+  // implementation. This lock must be set and must be held on every call into
+  // the GPU implementation if it is to be used from multiple threads. This
+  // may not be supported with all implementations.
+  virtual void SetLock(base::Lock*) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(GpuControl);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GPU_CONTROL_H_