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

third_party/WebKit/public/web/WebWidgetClient.h

 /*
  * Copyright (C) 2009 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 99 matching lines @@
     virtual WebRect windowResizerRect() { return WebRect(); }
 
     // Called to get the position of the root window containing the widget
     // in screen coordinates.
     virtual WebRect rootWindowRect() { return WebRect(); }
 
     // Called to query information about the screen where this widget is
     // displayed.
     virtual WebScreenInfo screenInfo() { return WebScreenInfo(); }
 
-    // Called to get the scale factor of the display.
-    virtual float deviceScaleFactor() { return 1; }
-
     // When this method gets called, WebWidgetClient implementation should
     // reset the input method by cancelling any ongoing composition.
     virtual void resetInputMethod() { }
 
     // Requests to lock the mouse cursor. If true is returned, the success
     // result will be asynchronously returned via a single call to
     // WebWidget::didAcquirePointerLock() or
     // WebWidget::didNotAcquirePointerLock().
     // If false, the request has been denied synchronously.
     virtual bool requestPointerLock() { return false; }
@@ skipping 45 matching lines @@
     // press or gesture tap.
     // Note: This is called even when the mouse down event is prevent default.
     virtual void onMouseDown(const WebNode& mouseDownNode) { }
 protected:
     ~WebWidgetClient() { }
 };
 
 } // namespace blink
 
 #endif