Introduce painted-device-scale-factor and use it when --enable-use-zoom-for-dsf is specified.

content/renderer/gpu/render_widget_compositor.h

Index: content/renderer/gpu/render_widget_compositor.h
diff --git a/content/renderer/gpu/render_widget_compositor.h b/content/renderer/gpu/render_widget_compositor.h
index ee101bb610df5f193a16638a355d28bcda56e73c..881d6bf93e02d11fa24200d24331fc07b22e41cf 100644
--- a/content/renderer/gpu/render_widget_compositor.h
+++ b/content/renderer/gpu/render_widget_compositor.h
@@ -89,9 +89,6 @@ class CONTENT_EXPORT RenderWidgetCompositor
       blink::WebCompositorAnimationTimeline* compositor_timeline) override;
   void detachCompositorAnimationTimeline(
       blink::WebCompositorAnimationTimeline* compositor_timeline) override;
-  virtual void setViewportSize(
-      const blink::WebSize& unused_deprecated,
-      const blink::WebSize& device_viewport_size);
   void setViewportSize(const blink::WebSize& device_viewport_size) override;
   virtual blink::WebFloatPoint adjustEventPointForPinchZoom(
       const blink::WebFloatPoint& point) const;