Implemented Missing Virtual Functions Declaration in DirectRenderer Class.

cc/output/direct_renderer.h

 // Copyright 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 CC_OUTPUT_DIRECT_RENDERER_H_
 #define CC_OUTPUT_DIRECT_RENDERER_H_
 
 #include <memory>
 #include <unordered_map>
 
@@ skipping 45 matching lines @@
                  float device_scale_factor,
                  const gfx::ColorSpace& device_color_space,
                  const gfx::Rect& device_viewport_rect,
                  const gfx::Rect& device_clip_rect);
 
   // Public interface implemented by subclasses.
   virtual void SwapBuffers(CompositorFrameMetadata metadata) = 0;
   virtual void SwapBuffersComplete() {}
   virtual void DidReceiveTextureInUseResponses(
       const gpu::TextureInUseResponses& responses) {}
+  virtual void ReceiveSwapBuffersAck(const CompositorFrameAck& ack) {}
 
   // Allow tests to enlarge the texture size of non-root render passes to
   // verify cases where the texture doesn't match the render pass size.
   void SetEnlargePassTextureAmountForTesting(const gfx::Size& amount) {
     enlarge_pass_texture_amount_ = amount;
   }
 
   // Public for tests that poke at internals.
   struct CC_EXPORT DrawingFrame {
     DrawingFrame();
@@ skipping 85 matching lines @@
   virtual void FinishDrawingFrame(DrawingFrame* frame) = 0;
   // If a pass contains a single tile draw quad and can be drawn without
   // a render pass (e.g. applying a filter directly to the tile quad)
   // return that quad, otherwise return null.
   virtual const TileDrawQuad* CanPassBeDrawnDirectly(const RenderPass* pass);
   virtual void FinishDrawingQuadList() {}
   virtual bool FlippedFramebuffer(const DrawingFrame* frame) const = 0;
   virtual void EnsureScissorTestEnabled() = 0;
   virtual void EnsureScissorTestDisabled() = 0;
   virtual void DidChangeVisibility() = 0;
+  virtual void DiscardBackbuffer() {}
+  virtual void EnsureBackbuffer() {}
+
   virtual void CopyCurrentRenderPassToBitmap(
       DrawingFrame* frame,
       std::unique_ptr<CopyOutputRequest> request) = 0;
 
   const RendererSettings* const settings_;
   OutputSurface* const output_surface_;
   ResourceProvider* const resource_provider_;
   // This can be replaced by test implementations.
   std::unique_ptr<OverlayProcessor> overlay_processor_;
 
@@ skipping 26 matching lines @@
  private:
   bool initialized_ = false;
   gfx::Size enlarge_pass_texture_amount_;
 
   DISALLOW_COPY_AND_ASSIGN(DirectRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_DIRECT_RENDERER_H_