Implement interest rects for synchronized paint.

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

Index: third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp b/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
index b8d3db51df7ab705eef68d3ba11ce75cf7700936..1547255fdd158e747041352edab0b340703e0ea5 100644
--- a/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
+++ b/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
@@ -292,7 +292,18 @@ void GraphicsLayer::setOffsetDoubleFromLayoutObject(const DoubleSize& offset, Sh
         setNeedsDisplay();
 }
 
-void GraphicsLayer::paintGraphicsLayerContents(GraphicsContext& context, const IntRect& clip)
+void GraphicsLayer::paintIfNeeded(GraphicsContext& context)
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintSynchronizedPaintingEnabled());
+    if (!m_client)
+        return;
+    if (firstPaintInvalidationTrackingEnabled())
+        m_debugInfo.clearAnnotatedInvalidateRects();
+    incrementPaintCount();
+    m_client->paintContentsIfNeeded(this, context, m_paintingPhase);
+}
+
+void GraphicsLayer::paint(GraphicsContext& context, const IntRect& clip)
 {
     if (!m_client)
         return;
@@ -1165,12 +1176,6 @@ void GraphicsLayer::setScrollableArea(ScrollableArea* scrollableArea, bool isVie
         m_layer->layer()->setScrollClient(this);
 }
 
-void GraphicsLayer::paint(GraphicsContext& context, const IntRect& clip)
-{
-    paintGraphicsLayerContents(context, clip);
-}
-
-
 void GraphicsLayer::notifyAnimationStarted(double monotonicTime, int group)
 {
     if (m_client)