Ozone: Avoid blocking in Swapbuffer Call.

ui/ozone/platform/dri/gbm_surfaceless.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_PLATFORM_DRI_GBM_SURFACELESS_H_
 #define UI_OZONE_PLATFORM_DRI_GBM_SURFACELESS_H_
 
 #include "ui/ozone/public/surface_ozone_egl.h"
 
 namespace gfx {
 class Size;
 }  // namespace gfx
 
 namespace ui {
 
 class DriWindowDelegate;
+class PageFilpEventHandler;
 
 // In surfaceless mode drawing and displaying happens directly through
 // NativePixmap buffers. CC would call into SurfaceFactoryOzone to allocate the
 // buffers and then call ScheduleOverlayPlane(..) to schedule the buffer for
 // presentation.
 class GbmSurfaceless : public SurfaceOzoneEGL {
  public:
-  GbmSurfaceless(DriWindowDelegate* window_delegate);
+  GbmSurfaceless(DriWindowDelegate* window_delegate,
+                 PageFilpEventHandler* handler = NULL);
   ~GbmSurfaceless() override;
 
   // SurfaceOzoneEGL:
   intptr_t GetNativeWindow() override;
   bool ResizeNativeWindow(const gfx::Size& viewport_size) override;
   bool OnSwapBuffers() override;
   scoped_ptr<gfx::VSyncProvider> CreateVSyncProvider() override;
+  void SetPageFlipCompletionCallback(
+      const PageFlipCompletionCallback& callback) override;
 
  protected:
   DriWindowDelegate* window_delegate_;
+  PageFilpEventHandler* flip_handler_;  // Not owned.
+  PageFlipCompletionCallback callback_;
 
   DISALLOW_COPY_AND_ASSIGN(GbmSurfaceless);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRI_GBM_SURFACELESS_H_