Plumb GpuSwapBuffers completion from Mus GPU thread to WS thread

components/mus/gles2/gl_surface_adapter.h

+// Copyright (c) 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.
+
+#ifndef COMPONENTS_MUS_GLES2_GL_SURFACE_ADAPTER_H_
+#define COMPONENTS_MUS_GLES2_GL_SURFACE_ADAPTER_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "ui/gfx/swap_result.h"
+#include "ui/gl/gl_surface.h"
+
+namespace mus {
+
+// Wraps a GLSurface using gfx::GLSurfaceAdapter.

[Fady Samuel, 2016/04/01 23:24:42]

nit: Better class level comments please. I'm not very familiar with
GLSurfaceAdapter so getting a high level description of the responsibilities of
this class would be super useful for future reference.

[rjkroege, 2016/04/01 23:58:44]

Done.

+class GLSurfaceAdapterMus : public gfx::GLSurfaceAdapter {
+ public:
+  explicit GLSurfaceAdapterMus(scoped_refptr<gfx::GLSurface> surface);
+  // GLSurfaceAdapterMus replaces the necessary entry points to observe the end
+  // of
+  // SwapBuffers.
+  void SwapBuffersAsync(
+      const gfx::GLSurface::SwapCompletionCallback& callback) override;
+  void PostSubBufferAsync(
+      int x,
+      int y,
+      int width,
+      int height,
+      const gfx::GLSurface::SwapCompletionCallback& callback) override;
+  void CommitOverlayPlanesAsync(
+      const gfx::GLSurface::SwapCompletionCallback& callback) override;
+
+  // Additional callback to run on SwapBuffers completion.
+  void SetGpuCompletedSwapBuffersCallback(
+      gfx::GLSurface::SwapCompletionCallback callback);
+
+ private:
+  ~GLSurfaceAdapterMus() override;
+
+  // We wrap the callback given to the GLSurface entry points above with an
+  // invocation of this function. It invokes |adapter_callback_| and the
+  // provided original |original_callback|
+  void WrappedCallbackForSwapBuffersAsync(
+      const gfx::GLSurface::SwapCompletionCallback& original_callback,
+      gfx::SwapResult result);
+
+  gfx::GLSurface::SwapCompletionCallback adapter_callback_;
+
+  // gfx::GLSurfaceAdapter doesn't own the delegate surface so keep a reference
+  // here.
+  scoped_refptr<gfx::GLSurface> surface_;
+
+  base::WeakPtrFactory<GLSurfaceAdapterMus> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(GLSurfaceAdapterMus);
+};
+
+}  // namespace mus
+
+#endif  // COMPONENTS_MUS_GLES2_GL_SURFACE_ADAPTER_H_