Use recomputed interest rect only if it changed enough

third_party/WebKit/Source/web/PageOverlay.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 78 matching lines @@
         page->frameHost().visualViewport().containerLayer()->addChild(m_layer.get());
     }
 
     FloatSize size = page->frameHost().visualViewport().size();
     if (size != m_layer->size())
         m_layer->setSize(size);
 
     m_layer->setNeedsDisplay();
 }
 
-void PageOverlay::paintContents(const GraphicsLayer* graphicsLayer, GraphicsContext& gc, GraphicsLayerPaintingPhase phase, const IntRect* inClip) const
+IntRect PageOverlay::paintContents(const GraphicsLayer* graphicsLayer, GraphicsContext& gc, GraphicsLayerPaintingPhase phase, const IntRect*) const
 {
     ASSERT(m_layer);
-    m_delegate->paintPageOverlay(*this, gc, expandedIntSize(m_layer->size()));
+    IntSize paintSize = expandedIntSize(m_layer->size());
+    m_delegate->paintPageOverlay(*this, gc, paintSize);
+    return IntRect(IntPoint(), paintSize);
 }
 
 String PageOverlay::debugName(const GraphicsLayer*)
 {
     return "WebViewImpl Page Overlay Content Layer";
 }
 
 } // namespace blink