Update from https://crrev.com/316786

gpu/command_buffer/client/gpu_control.h

Index: gpu/command_buffer/client/gpu_control.h
diff --git a/gpu/command_buffer/client/gpu_control.h b/gpu/command_buffer/client/gpu_control.h
index a56bd516fc570a7015ee9c1c9d45c16c12779adf..2b303b3b4d58ced50269d00d2598e29c248dcf4d 100644
--- a/gpu/command_buffer/client/gpu_control.h
+++ b/gpu/command_buffer/client/gpu_control.h
@@ -17,6 +17,10 @@
 
 extern "C" typedef struct _ClientBuffer* ClientBuffer;
 
+namespace base {
+class Lock;
+}
+
 namespace gfx {
 class GpuMemoryBuffer;
 }
@@ -75,6 +79,12 @@ class GPU_EXPORT GpuControl {
   // 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);
 };