Preliminary compositor disabling patch.

cc/trees/damage_tracker.h

Index: cc/trees/damage_tracker.h
diff --git a/cc/trees/damage_tracker.h b/cc/trees/damage_tracker.h
index aafbd033bcd0d0823a487e0390427920c7b7b4ce..0bee8f6f065fb9b464be31dc24222c87fb6a4e0e 100644
--- a/cc/trees/damage_tracker.h
+++ b/cc/trees/damage_tracker.h
@@ -31,7 +31,10 @@ class CC_EXPORT DamageTracker {
   static scoped_ptr<DamageTracker> Create();
   ~DamageTracker();
 
-  void DidDrawDamagedArea() { current_damage_rect_ = gfx::Rect(); }
+  void DidDrawDamagedArea() {
+    current_damage_rect_ = gfx::Rect();
+    current_overlay_rect_ = gfx::Rect();
+  }
   void AddDamageNextUpdate(const gfx::Rect& dmg) {
     current_damage_rect_.Union(dmg);
   }
@@ -44,19 +47,24 @@ class CC_EXPORT DamageTracker {
       const FilterOperations& filters);
 
   gfx::Rect current_damage_rect() { return current_damage_rect_; }
+  gfx::Rect current_overlay_rect() { return current_overlay_rect_; }
 
  private:
   DamageTracker();
 
-  gfx::Rect TrackDamageFromActiveLayers(const LayerImplList& layer_list,
-                                        int target_surface_layer_id);
+  void TrackDamageFromActiveLayers(const LayerImplList& layer_list,
+                                   int target_surface_layer_id,
+                                   gfx::Rect* damage,
+                                   gfx::Rect* overlay);
   gfx::Rect TrackDamageFromSurfaceMask(LayerImpl* target_surface_mask_layer);
   gfx::Rect TrackDamageFromLeftoverRects();
 
   void PrepareRectHistoryForUpdate();
 
   // These helper functions are used only in TrackDamageFromActiveLayers().
-  void ExtendDamageForLayer(LayerImpl* layer, gfx::Rect* target_damage_rect);
+  void ExtendDamageForLayer(LayerImpl* layer,
+                            gfx::Rect* target_damage_rect,
+                            gfx::Rect* target_overlay_rect);
   void ExtendDamageForRenderSurface(LayerImpl* layer,
                                     gfx::Rect* target_damage_rect);
 
@@ -84,6 +92,7 @@ class CC_EXPORT DamageTracker {
 
   unsigned int mailboxId_;
   gfx::Rect current_damage_rect_;
+  gfx::Rect current_overlay_rect_;
 
   DISALLOW_COPY_AND_ASSIGN(DamageTracker);
 };