vr/gpu: BrowserGpuChannelHostFactory should be called on the same thread.

chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h

 // Copyright 2017 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 CHROME_BROWSER_ANDROID_VR_SHELL_MAILBOX_TO_SURFACE_BRIDGE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_MAILBOX_TO_SURFACE_BRIDGE_H_
 
 #include "base/memory/weak_ptr.h"
 
 namespace gl {
+class ScopedJavaSurface;
 class SurfaceTexture;
 }
 
 namespace gpu {
 struct MailboxHolder;
 namespace gles2 {
 class GLES2Interface;
 }
 }
 
@@ skipping 11 matching lines @@
   void CreateSurface(gl::SurfaceTexture*);
 
   void ResizeSurface(int width, int height);
 
   // Returns true if swapped successfully. This can fail if the GL
   // context isn't ready for use yet, in that case the caller
   // won't get a new frame on the SurfaceTexture.
   bool CopyMailboxToSurfaceAndSwap(const gpu::MailboxHolder& mailbox);
 
  private:
-  void OnContextAvailable(scoped_refptr<cc::ContextProvider>);
+  void OnContextAvailable(std::unique_ptr<gl::ScopedJavaSurface> surface,
+                          scoped_refptr<cc::ContextProvider>);
   void InitializeRenderer();
   void DestroyContext();
   void DrawQuad(unsigned int textureHandle);
 
   scoped_refptr<cc::ContextProvider> context_provider_;
   gpu::gles2::GLES2Interface* gl_ = nullptr;
   int surface_handle_ = 0;
 
   // Saved state for a pending resize, the dimensions are only
   // valid if needs_resize_ is true.
   bool needs_resize_ = false;
   int resize_width_;
   int resize_height_;
 
   // Must be last.
   base::WeakPtrFactory<MailboxToSurfaceBridge> weak_ptr_factory_;
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_MAILBOX_TO_SURFACE_BRIDGE_H_