Compute damage rect for Cast video compositing

cc/output/overlay_processor.h

Index: cc/output/overlay_processor.h
diff --git a/cc/output/overlay_processor.h b/cc/output/overlay_processor.h
index 01c28d253174aca976d65bff43138477b5146c4b..ebe92053614bd476d78b46b91bf7de76e57d7d6d 100644
--- a/cc/output/overlay_processor.h
+++ b/cc/output/overlay_processor.h
@@ -29,6 +29,8 @@ class CC_EXPORT OverlayProcessor {
     virtual bool Attempt(ResourceProvider* resource_provider,
                          RenderPass* render_pass,
                          OverlayCandidateList* candidates) = 0;
+
+    virtual bool GetSwapWithDamageRect(gfx::Rect* rect);
   };
   using StrategyList = std::vector<std::unique_ptr<Strategy>>;
 
@@ -47,12 +49,17 @@ class CC_EXPORT OverlayProcessor {
                           CALayerOverlayList* ca_layer_overlays,
                           gfx::Rect* damage_rect);
 
+  bool GetSwapWithDamageRect(gfx::Rect* damage_rect);
+
  protected:
   StrategyList strategies_;
   OutputSurface* surface_;
   gfx::Rect overlay_damage_rect_;
   gfx::Rect previous_frame_underlay_rect_;
 
+  bool have_swap_with_damage_rect_;
+  gfx::Rect swap_with_damage_rect_;
+
  private:
   bool ProcessForCALayers(ResourceProvider* resource_provider,
                           RenderPass* render_pass,