Handle ui::Layer's visibility using cc::Layer's m_isDrawable flag

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 100 matching lines @@
 
     virtual ScrollbarLayerImpl* toScrollbarLayer();
 
     // Returns true if this layer has content to draw.
     void setDrawsContent(bool);
     bool drawsContent() const { return m_drawsContent; }
 
     bool forceRenderSurface() const { return m_forceRenderSurface; }
     void setForceRenderSurface(bool force) { m_forceRenderSurface = force; }
 
+    void setVisible(bool);
+    bool visible() const { return m_visible; }
+
     void setAnchorPoint(const gfx::PointF&);
     const gfx::PointF& anchorPoint() const { return m_anchorPoint; }
 
     void setAnchorPointZ(float);
     float anchorPointZ() const { return m_anchorPointZ; }
 
     void setBackgroundColor(SkColor);
     SkColor backgroundColor() const { return m_backgroundColor; }
 
     void setFilters(const WebKit::WebFilterOperations&);
@@ skipping 243 matching lines @@
     float m_opacity;
     gfx::PointF m_position;
     bool m_preserves3D;
     bool m_useParentBackfaceVisibility;
     bool m_drawCheckerboardForMissingTiles;
     gfx::Transform m_sublayerTransform;
     gfx::Transform m_transform;
 
     bool m_drawsContent;
     bool m_forceRenderSurface;
+    bool m_visible;
 
     // Set for the layer that other layers are fixed to.
     bool m_isContainerForFixedPositionLayers;
     // This is true if the layer should be fixed to the closest ancestor container.
     bool m_fixedToContainerLayer;
 
     gfx::Vector2dF m_scrollDelta;
     gfx::Vector2d m_sentScrollDelta;
     gfx::Vector2d m_maxScrollOffset;
     gfx::Transform m_implTransform;
@@ skipping 33 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_