ozone: Add OnSwapBuffers hook to SurfaceOzoneEGL

ui/gfx/ozone/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_GFX_OZONE_SURFACE_OZONE_EGL_H_
 #define UI_GFX_OZONE_SURFACE_OZONE_EGL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/gfx_export.h"
@@ skipping 12 matching lines @@
   virtual ~SurfaceOzoneEGL() {}
 
   // Returns the EGL native window for rendering onto this surface.
   // This can be used to to create a GLSurface.
   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;
+
   // 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 gfx
 
 #endif  // UI_GFX_OZONE_SURFACE_OZONE_EGL_H_