Prevent image downscaling on HiDPI devices with impl-side painting.

Source/Platform/chromium/public/WebContentLayerClient.h

Index: Source/Platform/chromium/public/WebContentLayerClient.h
diff --git a/Source/Platform/chromium/public/WebContentLayerClient.h b/Source/Platform/chromium/public/WebContentLayerClient.h
index 5641a4eb675c2160b589f2050311877757e69490..a3cd8ceace60af2da3d6fe1f3dc872ed6653e3f0 100644
--- a/Source/Platform/chromium/public/WebContentLayerClient.h
+++ b/Source/Platform/chromium/public/WebContentLayerClient.h
@@ -41,7 +41,7 @@ public:
     // Optionally, the implementation may set |opaque| to a rect covering pixels that
     // the implementation knows are opaque. This information can be used for various
     // optimizations.
-    virtual void paintContents(WebCanvas*, const WebRect& clip, bool canPaintLCDText, WebFloatRect& opaque) = 0;
+    virtual void paintContents(WebCanvas*, const WebRect& clip, bool canPaintLCDText, WebFloatRect& opaque, bool deferred = false) = 0;
 
 protected:
     virtual ~WebContentLayerClient() { }