Set the device scale factor from the compositor interface

content/public/browser/android/compositor.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_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_
 #define CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_
 
 #include "base/callback.h"
 #include "content/common/content_export.h"
 #include "ui/gfx/native_widget_types.h"
@@ skipping 42 matching lines @@
   // Initialize with flags. This should only be called once instead
   // of Initialize().
   static void InitializeWithFlags(uint32 flags);
 
   // Creates and returns a compositor instance.
   static Compositor* Create(Client* client);
 
   // Attaches the layer tree.
   virtual void SetRootLayer(scoped_refptr<cc::Layer> root) = 0;
 
+  // Set the scale factor from dp to pixel.

[aelias_OOO_until_Jul13, 2013/02/12 00:16:07]

Nit: we usually write "DIP" (for "density independent pixel") instead of "dp".

+  virtual void setDeviceScaleFactor(float factor) = 0;
+
   // Set the output surface bounds.
   virtual void SetWindowBounds(const gfx::Size& size) = 0;
 
   // Sets the window visibility. When becoming invisible, resources will get
   // freed and other calls into the compositor are not allowed until after
   // having been made visible again.
   virtual void SetVisible(bool visible) = 0;
 
   // Set the output surface handle which the compositor renders into.
   virtual void SetWindowSurface(ANativeWindow* window) = 0;
@@ skipping 34 matching lines @@
   virtual bool CopyTextureToBitmap(WebKit::WebGLId texture_id,
                                    const gfx::Rect& src_rect,
                                    gfx::JavaBitmap& bitmap) = 0;
  protected:
   Compositor() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_