Use SwapBuffersWithBounds on Chromecast

cc/output/output_surface_frame.h

Index: cc/output/output_surface_frame.h
diff --git a/cc/output/output_surface_frame.h b/cc/output/output_surface_frame.h
index 331496fe06ebfb7b385e259098125fce7cf49943..3133e8e260d0bbffdc781a4951cd773ecbac52d3 100644
--- a/cc/output/output_surface_frame.h
+++ b/cc/output/output_surface_frame.h
@@ -27,8 +27,12 @@ class CC_EXPORT OutputSurfaceFrame {
   OutputSurfaceFrame& operator=(OutputSurfaceFrame&& other);
 
   gfx::Size size;
-  // Optional rect for partial or empty swap; if not provided, use regular swap.
+  // Providing both |sub_buffer_rect| and |content_bounds| is not supported;
+  // if neither is present, regular swap is used.
+  // Optional rect for partial or empty swap.
   base::Optional<gfx::Rect> sub_buffer_rect;
+  // Optional content area for SwapWithBounds. Rectangles may overlap.
+  std::vector<gfx::Rect> content_bounds;
   std::vector<ui::LatencyInfo> latency_info;
 
  private: