implement getBufferSubDataAsync prototype

third_party/WebKit/Source/platform/graphics/test/FakeWebGraphicsContext3DProvider.h

 // Copyright 2016 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.
 
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/common/capabilities.h"
 #include "public/platform/WebGraphicsContext3DProvider.h"
 #include "third_party/skia/include/gpu/GrContext.h"
 #include "third_party/skia/include/gpu/gl/GrGLInterface.h"
 #include "wtf/RefPtr.h"
@@ skipping 15 matching lines @@
   gpu::Capabilities getCapabilities() override { return gpu::Capabilities(); }
 
   bool isSoftwareRendering() const override { return false; }
 
   gpu::gles2::GLES2Interface* contextGL() override { return m_gl; }
 
   bool bindToCurrentThread() override { return false; }
   void setLostContextCallback(const base::Closure&) override {}
   void setErrorMessageCallback(
       const base::Callback<void(const char*, int32_t id)>&) {}
+  void signalQuery(uint32_t, const base::Closure&) override {}
 
  private:
   gpu::gles2::GLES2Interface* m_gl;
   RefPtr<GrContext> m_grContext;
 };
 
 }  // namespace blink