Make new-style page scale work on Android.

cc/pinch_zoom_viewport.cc

 // 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.
 
 #include "cc/pinch_zoom_viewport.h"
 
 #include "base/logging.h"
 
 namespace cc {
 
@@ skipping 32 matching lines @@
       max_page_scale_factor == max_page_scale_factor_)
     return false;
 
   min_page_scale_factor_ = min_page_scale_factor;
   max_page_scale_factor_ = max_page_scale_factor;
 
   page_scale_factor_ = page_scale_factor;
   return true;
 }
 
-gfx::RectF PinchZoomViewport::Bounds() const {
-  gfx::RectF bounds(gfx::PointF(), layout_viewport_size_);
-  bounds.Scale(1 / total_page_scale_factor());
-  bounds += zoomed_viewport_offset_;
-  return bounds;
+gfx::RectF PinchZoomViewport::ZoomedViewport() const {
+  gfx::SizeF layout_space_device_viewport_size = gfx::ScaleSize(
+      device_viewport_size_,
+      1 / (device_scale_factor_ * total_page_scale_factor()));
+  return gfx::RectF(gfx::PointAtOffsetFromOrigin(zoomed_viewport_offset_),
+                    layout_space_device_viewport_size);
 }
 
 gfx::Vector2dF PinchZoomViewport::ApplyScroll(const gfx::Vector2dF delta) {
   gfx::Vector2dF overflow;
-  gfx::RectF pinched_bounds = Bounds() + delta;
+  gfx::RectF pinched_bounds = ZoomedViewport() + delta;
 
   if (pinched_bounds.x() < 0) {
     overflow.set_x(pinched_bounds.x());
     pinched_bounds.set_x(0);
   }
 
   if (pinched_bounds.y() < 0) {
     overflow.set_y(pinched_bounds.y());
     pinched_bounds.set_y(0);
   }
@@ skipping 28 matching lines @@
     gfx::Vector2dF zoomed_device_viewport_offset
       = gfx::ScaleVector2d(zoomed_viewport_offset_, device_scale_factor_);
     transform.Translate(-zoomed_device_viewport_offset.x(),
                         -zoomed_device_viewport_offset.y());
   }
 
   return transform;
 }
 
 }  // namespace cc