Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

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 "cc/pinch_zoom_scrollbar_layer_impl.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
+class LayerTreeHostImpl;
+
 // PinchZoomViewport models the bounds and offset of the viewport that is used
 // during a pinch-zoom operation. It tracks the layout-space dimensions of the
 // viewport before any applied scale, and then tracks the layout-space
 // coordinates of the viewport respecting the pinch settings.
 class CC_EXPORT PinchZoomViewport {
  public:
-  PinchZoomViewport();
+  PinchZoomViewport(LayerTreeHostImpl*);
+  ~PinchZoomViewport();
 
   float total_page_scale_factor() const {
     return page_scale_factor_ * page_scale_delta_;
   }
 
   void set_page_scale_factor(float factor) { page_scale_factor_ = factor; }
   float page_scale_factor() const { return page_scale_factor_; }
 
   void set_page_scale_delta(float delta);
   float page_scale_delta() const  { return page_scale_delta_; }
@@ skipping 20 matching lines @@
   // for pinch-zoom.
   gfx::RectF Bounds() 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;
   }
+  gfx::SizeF layout_viewport_size() {
+    return layout_viewport_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;
 
+  LayerImpl* root_scroll_layer();
+  LayerImpl* currently_scrolling_layer() const;
+
+  void AddPinchZoomScrollbarsToTree(LayerTreeImpl*);
+
  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_;
+
+  PinchZoomScrollbarState vertical_scrollbar_client_;
+  PinchZoomScrollbarState horizontal_scrollbar_client_;
+  LayerTreeHostImpl* owner_;
 };
 
 }  // namespace cc
 
 #endif  // CC_PINCH_ZOOM_VIEWPORT_H_