Make new-style page scale work on Android.

cc/pinch_zoom_viewport.h

 // Copyright 2013 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 CC_PINCH_ZOOM_VIEWPORT_H_
 #define CC_PINCH_ZOOM_VIEWPORT_H_
 
 #include "cc/cc_export.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
@@ skipping 29 matching lines @@
 
   void set_device_scale_factor(float factor) { device_scale_factor_ = factor; }
   float device_scale_factor() const { return device_scale_factor_; }
 
   // Returns true if the passed parameters were different from those previously
   // cached.
   bool SetPageScaleFactorAndLimits(float page_scale_factor,
                                    float min_page_scale_factor,
                                    float max_page_scale_factor);
 
-  // Returns the bounds and offset of the scaled and translated viewport to use
-  // for pinch-zoom.
-  gfx::RectF Bounds() const;
+  // Returns the zoomed viewport in layout space. The rect's position is an
+  // offset from the root layer's scroll position (therefore, zero if fully
+  // zoomed out).
+  gfx::RectF ZoomedViewport() const;
 
   const gfx::Vector2dF& zoomed_viewport_offset() const {
     return zoomed_viewport_offset_;
   }
 
   void set_layout_viewport_size(const gfx::SizeF& size) {
     layout_viewport_size_ = size;
   }
+  void set_device_viewport_size(const gfx::SizeF& size) {

[wjmaclean, 2013/01/17 19:45:52]

Perhaps add a comment explaining why we need to store this, as opposed to just
converting layout_viewport_size_ using psf and dsf. 

[aelias_OOO_until_Jul13, 2013/01/17 19:59:46]

Done.

+    device_viewport_size_ = size;
+  }
 
   // Apply the scroll offset in layout space to the offset of the pinch-zoom
   // viewport. The viewport cannot be scrolled outside of the layout viewport
   // bounds. Returns the component of the scroll that is un-applied due to this
   // constraint.
   gfx::Vector2dF ApplyScroll(const gfx::Vector2dF);
 
   // The implTransform goes from the origin of the unzoomedDeviceViewport to the
   // origin of the zoomedDeviceViewport.
   //
   // implTransform = S[pageScale] * Tr[-zoomedDeviceViewportOffset]
   gfx::Transform ImplTransform(bool page_scale_pinch_zoom_enabled) const;
 
  private:
   float page_scale_factor_;
   float page_scale_delta_;
   float sent_page_scale_delta_;
   float max_page_scale_factor_;
   float min_page_scale_factor_;
   float device_scale_factor_;
 
   gfx::Vector2dF zoomed_viewport_offset_;
   gfx::SizeF layout_viewport_size_;
+  gfx::SizeF device_viewport_size_;
 };
 
 }  // namespace cc
 
 #endif  // CC_PINCH_ZOOM_VIEWPORT_H_