Turn off computation of the interest rect in cc in synchronized paint mode.

third_party/WebKit/Source/platform/graphics/ContentLayerDelegate.h

Index: third_party/WebKit/Source/platform/graphics/ContentLayerDelegate.h
diff --git a/third_party/WebKit/Source/platform/graphics/ContentLayerDelegate.h b/third_party/WebKit/Source/platform/graphics/ContentLayerDelegate.h
index e07ce0d0ef16feff969e8a4141cd76318f5e8f69..16a681a6dd4891f100590ad8868bdb296759fe6a 100644
--- a/third_party/WebKit/Source/platform/graphics/ContentLayerDelegate.h
+++ b/third_party/WebKit/Source/platform/graphics/ContentLayerDelegate.h
@@ -33,6 +33,10 @@
 
 class SkCanvas;
 
+namespace gfx {
+class Rect;
+}
+
 namespace blink {
 
 class GraphicsContext;
@@ -41,6 +45,7 @@ class PaintController;
 
 class PLATFORM_EXPORT GraphicsContextPainter {
 public:
+    virtual IntRect interestRect() = 0;
     virtual void paint(GraphicsContext&, const IntRect* interestRect) = 0;
     virtual PaintController* paintController() = 0;
 
@@ -55,6 +60,8 @@ public:
     explicit ContentLayerDelegate(GraphicsContextPainter*);
     ~ContentLayerDelegate() override;
 
+    gfx::Rect paintableRegion() override;
+
     // WebContentLayerClient implementation.
     void paintContents(WebDisplayItemList*, const WebRect& clip, WebContentLayerClient::PaintingControlSetting = PaintDefaultBehavior) override;
     size_t approximateUnsharedMemoryUsage() const override;