cc: Allow the main thread to cancel commits

cc/trees/layer_tree_host.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_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <limits>
 #include <vector>
 
@@ skipping 149 matching lines @@
 
   void CollectRenderingStats(RenderingStats* stats) const;
 
   RenderingStatsInstrumentation* rendering_stats_instrumentation() const {
     return rendering_stats_instrumentation_.get();
   }
 
   const RendererCapabilities& GetRendererCapabilities() const;
 
   void SetNeedsAnimate();
+  virtual void SetNeedsUpdateLayers();
   virtual void SetNeedsCommit();
   virtual void SetNeedsFullTreeSync();
   void SetNeedsRedraw();
   void SetNeedsRedrawRect(gfx::Rect damage_rect);
   bool CommitRequested() const;
 
   void SetAnimationEvents(scoped_ptr<AnimationEventsVector> events,
                           base::Time wall_clock_time);
 
   void SetRootLayer(scoped_refptr<Layer> root_layer);
   Layer* root_layer() { return root_layer_.get(); }
   const Layer* root_layer() const { return root_layer_.get(); }
 
   const LayerTreeSettings& settings() const { return settings_; }
 
   void SetDebugState(const LayerTreeDebugState& debug_state);
   const LayerTreeDebugState& debug_state() const { return debug_state_; }
 
   void SetViewportSize(gfx::Size device_viewport_size);
   void SetOverdrawBottomHeight(float overdraw_bottom_height);
 
   gfx::Size device_viewport_size() const { return device_viewport_size_; }
   float overdraw_bottom_height() const { return overdraw_bottom_height_; }
 
+  void ApplyPageScaleDeltaFromImplSide(float page_scale_delta);
   void SetPageScaleFactorAndLimits(float page_scale_factor,
                                    float min_page_scale_factor,
                                    float max_page_scale_factor);
   float page_scale_factor() const { return page_scale_factor_; }
 
   SkColor background_color() const { return background_color_; }
   void set_background_color(SkColor color) { background_color_ = color; }
 
   void set_has_transparent_background(bool transparent) {
     has_transparent_background_ = transparent;
@@ skipping 164 matching lines @@
     int64 total_num_cc_layers_will_use_lcd_text;
   };
   LCDTextMetrics lcd_text_metrics_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_