mac: Make dynamic DPI changes work.

content/renderer/render_widget.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_WIDGET_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 #pragma once
 
 #include <deque>
 #include <vector>
@@ skipping 236 matching lines @@
       const std::vector<WebKit::WebCompositionUnderline>& underlines,
       int selection_start,
       int selection_end);
   virtual void OnImeConfirmComposition(
       const string16& text, const ui::Range& replacement_range);
   void OnMsgPaintAtSize(const TransportDIB::Handle& dib_id,
                         int tag,
                         const gfx::Size& page_size,
                         const gfx::Size& desired_size);
   void OnMsgRepaint(const gfx::Size& size_to_paint);
-  void OnSetDeviceScaleFactor(float device_scale_factor);
+  virtual void OnSetDeviceScaleFactor(float device_scale_factor);
   void OnSetTextDirection(WebKit::WebTextDirection direction);
   void OnGetFPS();
 
   // Override points to notify derived classes that a paint has happened.
   // WillInitiatePaint happens when we're about to generate a new bitmap and
   // send it to the browser. DidInitiatePaint happens when that has completed,
   // and subsequent rendering won't affect the painted content. DidFlushPaint
   // happens once we've received the ACK that the screen has been updated.
   // For a given paint operation, these overrides will always be called in the
   // order WillInitiatePaint, DidInitiatePaint, DidFlushPaint.
@@ skipping 286 matching lines @@
   WebKit::WebScreenInfo screen_info_;
 
   // The device scale factor. This value is computed from the DPI entries in
   // |screen_info_| on some platforms, and defaults to 1 on other platforms.
   int device_scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_H_