Add support to delay sending SwapbufferAck as needed.

ui/gl/gl_surface.h

 // Copyright (c) 2012 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 UI_GL_GL_SURFACE_H_
 #define UI_GL_GL_SURFACE_H_
 
 #include <string>
 
+#include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "build/build_config.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/overlay_transform.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/rect_f.h"
 #include "ui/gfx/size.h"
 #include "ui/gl/gl_export.h"
 #include "ui/gl/gl_implementation.h"
 
@@ skipping 45 matching lines @@
   // Get the underlying platform specific surface "handle".
   virtual void* GetHandle() = 0;
 
   // Returns whether or not the surface supports PostSubBuffer.
   virtual bool SupportsPostSubBuffer();
 
   // Returns the internal frame buffer object name if the surface is backed by
   // FBO. Otherwise returns 0.
   virtual unsigned int GetBackingFrameBufferObject();
 
+  typedef base::Callback<void()> SwapCompletionCallback;
+  // Swaps front and back buffers. This has no effect for off-screen
+  // contexts. On some platforms, we want to send SwapBufferAck only after the
+  // surface is displayed on screen. The callback can be used to delay sending
+  // SwapBufferAck till that data is available. The callback should be run on
+  // GPUMainThread only.

[piman, 2014/12/22 20:53:15]

nit: in ui/gl there's no notion of GpuMainThread.
I would phrase it as: the callback should be run on the calling thread (i.e.
same thread SwapBuffersAsync is called).

[kalyank, 2014/12/23 11:22:42]

Done.

+  virtual bool SwapBuffersAsync(const SwapCompletionCallback& callback);
+
   // Copy part of the backbuffer to the frontbuffer.
   virtual bool PostSubBuffer(int x, int y, int width, int height);
 
+  // Copy part of the backbuffer to the frontbuffer. On some platforms, we want
+  // to send SwapBufferAck only after the surface is displayed on screen. The
+  // callback can be used to delay sending SwapBufferAck till that data is
+  // available. The callback should be run on GPUMainThread only.
+  virtual bool PostSubBufferAsync(int x,
+                                  int y,
+                                  int width,
+                                  int height,
+                                  const SwapCompletionCallback& callback);
+
   // Initialize GL bindings.
   static bool InitializeOneOff();
 
   // Unit tests should call these instead of InitializeOneOff() to set up
   // GL bindings appropriate for tests.
   static void InitializeOneOffForTests();
   static void InitializeOneOffWithMockBindingsForTests();
   static void InitializeDynamicMockBindingsForTests(GLContext* context);
 
   // Called after a context is made current with this surface. Returns false
@@ skipping 78 matching lines @@
  public:
   explicit GLSurfaceAdapter(GLSurface* surface);
 
   bool Initialize() override;
   void Destroy() override;
   bool Resize(const gfx::Size& size) override;
   bool Recreate() override;
   bool DeferDraws() override;
   bool IsOffscreen() override;
   bool SwapBuffers() override;
+  bool SwapBuffersAsync(const SwapCompletionCallback& callback) override;
   bool PostSubBuffer(int x, int y, int width, int height) override;
+  bool PostSubBufferAsync(int x,
+                          int y,
+                          int width,
+                          int height,
+                          const SwapCompletionCallback& callback) override;
   bool SupportsPostSubBuffer() override;
   gfx::Size GetSize() override;
   void* GetHandle() override;
   unsigned int GetBackingFrameBufferObject() override;
   bool OnMakeCurrent(GLContext* context) override;
   bool SetBackbufferAllocation(bool allocated) override;
   void SetFrontbufferAllocation(bool allocated) override;
   void* GetShareHandle() override;
   void* GetDisplay() override;
   void* GetConfig() override;
@@ skipping 13 matching lines @@
 
  private:
   scoped_refptr<GLSurface> surface_;
 
   DISALLOW_COPY_AND_ASSIGN(GLSurfaceAdapter);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_SURFACE_H_