Tag TransportDIBs with the device scale factor they expect.

content/browser/renderer_host/backing_store.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_BROWSER_RENDERER_HOST_BACKING_STORE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 27 matching lines @@
     return render_widget_host_;
   }
   const gfx::Size& size() { return size_; }
 
   // The number of bytes that this backing store consumes. The default
   // implementation just assumes there's 32 bits per pixel over the current
   // size of the screen. Implementations may override this if they have more
   // information about the color depth.
   virtual size_t MemorySize();
 
   // Paints the bitmap from the renderer onto the backing store.  bitmap_rect

[Avi (use Gerrit), 2012/06/13 20:44:40]

One space after period to match rest of comment.

[Nico, 2012/06/13 20:46:58]

Done.

   // gives the location of bitmap, and copy_rects specifies the subregion(s) of
-  // the backingstore to be painted from the bitmap.
+  // the backingstore to be painted from the bitmap. All coordinates are in
+  // DIPs. |scale_factor| contains the expected device scale factor of the
+  // backing store.
   //
   // PaintToBackingStore does not need to guarantee that this has happened by
   // the time it returns, in which case it will set |scheduled_callback| to
   // true and will call |callback| when completed.
   virtual void PaintToBackingStore(
       content::RenderProcessHost* process,
       TransportDIB::Id bitmap,
       const gfx::Rect& bitmap_rect,
       const std::vector<gfx::Rect>& copy_rects,
+      float scale_factor,
       const base::Closure& completion_callback,
       bool* scheduled_completion_callback) = 0;
 
   // Extracts the gives subset of the backing store and copies it to the given
   // PlatformCanvas. The PlatformCanvas should not be initialized. This function
   // will call initialize() with the correct size. The return value indicates
   // success.
   virtual bool CopyFromBackingStore(const gfx::Rect& rect,
                                     skia::PlatformCanvas* output) = 0;
 
@@ skipping 10 matching lines @@
   // The owner of this backing store.
   content::RenderWidgetHost* render_widget_host_;
 
   // The size of the backing store.
   gfx::Size size_;
 
   DISALLOW_COPY_AND_ASSIGN(BackingStore);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_H_