Drag image should always use the real device scale factor

content/renderer/render_view_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_RENDER_VIEW_IMPL_H_
 #define CONTENT_RENDERER_RENDER_VIEW_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 368 matching lines @@
   void focusedNodeChanged(const blink::WebNode& fromNode,
                           const blink::WebNode& toNode) override;
   void didUpdateLayout() override;
 #if defined(OS_ANDROID)
   bool didTapMultipleTargets(
       const blink::WebSize& inner_viewport_offset,
       const blink::WebRect& touch_rect,
       const blink::WebVector<blink::WebRect>& target_rects) override;
 #endif
   blink::WebString acceptLanguages() override;
+  float nonEmulatedDeviceScaleFactor() override;
   void navigateBackForwardSoon(int offset) override;
   int historyBackListCount() override;
   int historyForwardListCount() override;
   blink::WebSpeechRecognizer* speechRecognizer() override;
   void zoomLimitsChanged(double minimum_level, double maximum_level) override;
   virtual void zoomLevelChanged();
   void pageScaleFactorChanged() override;
   virtual double zoomLevelToZoomFactor(double zoom_level) const;
   virtual double zoomFactorToZoomLevel(double factor) const;
   blink::WebPageVisibilityState visibilityState() const override;
@@ skipping 580 matching lines @@
   // use the Observer interface to filter IPC messages and receive frame change
   // notifications.
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(RenderViewImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_VIEW_IMPL_H_