Tag TransportDIBs with the device scale factor they expect.

content/browser/renderer_host/backing_store_manager.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_MANAGER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 21 matching lines @@
   // backing_store_rect
   //   The desired backing store dimensions.
   // Returns a pointer to the backing store on success, NULL on failure.
   static BackingStore* GetBackingStore(content::RenderWidgetHost* host,
                                        const gfx::Size& desired_size);
 
   // Makes a backing store which is fully ready for consumption, i.e. the
   // bitmap from the renderer has been copied into the backing store.
   //
   // backing_store_size
-  //   The desired backing store dimensions.
+  //   The desired backing store dimensions, in DIPs.
   // bitmap_section
   //   The bitmap section from the renderer.
   // bitmap_rect
-  //   The rect to be painted into the backing store
+  //   The rect to be painted into the backing store, in DIPs.
+  // scale_factor
+  //   The device scale facctor the backing store is expected to be at.

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

s/facctor/factor/

+  //   If the backing store's device scale factor doesn't match, it will need
+  //   to scale |bitmap| at paint time. This will only be out of sync with the
+  //   backing store scale factor for a few frames, right after device scale
+  //   changes.
   // needs_full_paint
   //   Set if we need to send out a request to paint the view
   //   to the renderer.
   static void PrepareBackingStore(
       content::RenderWidgetHost* host,
       const gfx::Size& backing_store_size,
       TransportDIB::Id bitmap,
       const gfx::Rect& bitmap_rect,
       const std::vector<gfx::Rect>& copy_rects,
+      float scale_factor,
       const base::Closure& completion_callback,
       bool* needs_full_paint,
       bool* scheduled_completion_callback);
 
   // Returns a matching backing store for the host.
   // Returns NULL if we fail to find one.
   static BackingStore* Lookup(content::RenderWidgetHost* host);
 
   // Removes the backing store for the host.
   static void RemoveBackingStore(content::RenderWidgetHost* host);
 
   // Removes all backing stores.
   static void RemoveAllBackingStores();
 
   // Current size in bytes of the backing store cache.
   static size_t MemorySize();
 
  private:
   // Not intended for instantiation.
   BackingStoreManager() {}
 
   DISALLOW_COPY_AND_ASSIGN(BackingStoreManager);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_