Ozone: Avoid blocking in Swapbuffer Call.

ui/ozone/public/surface_ozone_egl.h

 // Copyright 2014 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_OZONE_PUBLIC_SURFACE_OZONE_EGL_H_
 #define UI_OZONE_PUBLIC_SURFACE_OZONE_EGL_H_
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/overlay_transform.h"
 #include "ui/ozone/ozone_base_export.h"
 
 namespace gfx {
 class Size;
 class VSyncProvider;
 }
 
 namespace ui {
@@ skipping 12 matching lines @@
   virtual intptr_t /* EGLNativeWindowType */ GetNativeWindow() = 0;
 
   // Attempts to resize the EGL native window to match the viewport
   // size.
   virtual bool ResizeNativeWindow(const gfx::Size& viewport_size) = 0;
 
   // Called after we swap buffers. This is usually a no-op but can
   // be used to present the new front buffer if the platform requires this.
   virtual bool OnSwapBuffers() = 0;
 
+  typedef base::Callback<void()> PageFlipCompletionCallback;
+  // On platforms where Chromium manages the system front/back buffer, we need
+  // to know when front buffer is actually displayed on screen. This
+  // callback should be called after the front buffer is displayed on screen.
+  virtual void SetPageFlipCompletionCallback(
+      const PageFlipCompletionCallback& callback) = 0;
+
   // Returns a gfx::VsyncProvider for this surface. Note that this may be
   // called after we have entered the sandbox so if there are operations (e.g.
   // opening a file descriptor providing vsync events) that must be done
   // outside of the sandbox, they must have been completed in
   // InitializeHardware. Returns an empty scoped_ptr on error.
   virtual scoped_ptr<gfx::VSyncProvider> CreateVSyncProvider() = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_SURFACE_OZONE_EGL_H_