cc: Use maximum tiling contents scales for picture layer scale

cc/layer_impl.h

 // Copyright 2011 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_LAYER_IMPL_H_
 #define CC_LAYER_IMPL_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 180 matching lines @@
     void setBounds(const gfx::Size&);
     const gfx::Size& bounds() const { return m_bounds; }
 
     void setContentBounds(const gfx::Size&);
     gfx::Size contentBounds() const { return m_drawProperties.content_bounds; }
 
     float contentsScaleX() const { return m_drawProperties.contents_scale_x; }
     float contentsScaleY() const { return m_drawProperties.contents_scale_y; }
     void setContentsScale(float contentsScaleX, float contentsScaleY);
 
+    virtual void calculateContentsScale(
+        float idealContentsScale,
+        float* contentsScaleX,
+        float* contentsScaleY,
+        gfx::Size* contentBounds);
+
     gfx::Vector2d scrollOffset() const { return m_scrollOffset; }
     void setScrollOffset(gfx::Vector2d);
 
     gfx::Vector2d maxScrollOffset() const {return m_maxScrollOffset; }
     void setMaxScrollOffset(gfx::Vector2d);
 
     const gfx::Vector2dF& scrollDelta() const { return m_scrollDelta; }
     void setScrollDelta(const gfx::Vector2dF&);
 
     const gfx::Transform& implTransform() const { return m_implTransform; }
@@ skipping 187 matching lines @@
     // Group of properties that need to be computed based on the layer tree
     // hierarchy before layers can be drawn.
     DrawProperties<LayerImpl, RenderSurfaceImpl> m_drawProperties;
 
     DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }
 
 #endif  // CC_LAYER_IMPL_H_