Implement desktop compatibility viewport

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 25 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);
 
+  const gfx::SizeF& layout_viewport_size() const { return layout_viewport_size_; }
   void set_layout_viewport_size(const gfx::SizeF& size) {
     layout_viewport_size_ = size;
   }
   // We need to store device_viewport_size separately because in mobile
   // fixed-layout mode, there is not necessarily a simple mapping between layout
   // viewport size and device viewport size.
   void set_device_viewport_size(const gfx::SizeF& size) {
     device_viewport_size_ = size;
   }
 
@@ skipping 12 matching lines @@
   float min_page_scale_factor_;
   float device_scale_factor_;
 
   gfx::SizeF layout_viewport_size_;
   gfx::SizeF device_viewport_size_;
 };
 
 }  // namespace cc
 
 #endif  // CC_PINCH_ZOOM_VIEWPORT_H_