Adding fading effect for paint rectangles in HUD.

cc/layers/heads_up_display_layer_impl.h

Index: cc/layers/heads_up_display_layer_impl.h
diff --git a/cc/layers/heads_up_display_layer_impl.h b/cc/layers/heads_up_display_layer_impl.h
index 47afa1fd73af2ba4d28b6bf9128be34a06bca650..2a81ded56c8ea1657340f5ce6ed1884f55235429 100644
--- a/cc/layers/heads_up_display_layer_impl.h
+++ b/cc/layers/heads_up_display_layer_impl.h
@@ -10,6 +10,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
+#include "cc/debug/debug_rect_history.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/resources/memory_history.h"
 #include "cc/resources/scoped_resource.h"
@@ -21,7 +22,6 @@ struct SkRect;
 
 namespace cc {
 
-class DebugRectHistory;
 class FrameRateCounter;
 class PaintTimeCounter;
 
@@ -47,6 +47,8 @@ class CC_EXPORT HeadsUpDisplayLayerImpl : public LayerImpl {
 
   virtual bool LayerIsAlwaysDamaged() const OVERRIDE;
 
+  bool NeedsUpdate() const { return needs_update_; }
+
  private:
   class Graph {
    public:
@@ -73,7 +75,7 @@ class CC_EXPORT HeadsUpDisplayLayerImpl : public LayerImpl {
   virtual void AsValueInto(base::DictionaryValue* dict) const OVERRIDE;
 
   void UpdateHudContents();
-  void DrawHudContents(SkCanvas* canvas) const;
+  void DrawHudContents(SkCanvas* canvas);
 
   void DrawText(SkCanvas* canvas,
                 SkPaint* paint,
@@ -108,8 +110,13 @@ class CC_EXPORT HeadsUpDisplayLayerImpl : public LayerImpl {
                               const PaintTimeCounter* paint_time_counter,
                               int top,
                               int right) const;
-  void DrawDebugRects(SkCanvas* canvas,
-                      DebugRectHistory* debug_rect_history) const;
+  void DrawDebugRect(SkCanvas* canvas,
+                     const DebugRect& rect,
+                     const SkColor stroke_color,
+                     const SkColor fill_color,
+                     const float stroke_width,
+                     const std::string label_text) const;
+  void DrawDebugRects(SkCanvas* canvas, DebugRectHistory* debug_rect_history);
 
   scoped_ptr<ScopedResource> hud_resource_;
   scoped_ptr<SkCanvas> hud_canvas_;
@@ -119,6 +126,7 @@ class CC_EXPORT HeadsUpDisplayLayerImpl : public LayerImpl {
   Graph fps_graph_;
   Graph paint_time_graph_;
   MemoryHistory::Entry memory_entry_;
+  bool needs_update_;
 
   base::TimeTicks time_of_last_graph_update_;