HUD: Show first paint invalidation in red

cc/layers/heads_up_display_layer_impl.cc

 // Copyright 2012 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.
 
 #include "cc/layers/heads_up_display_layer_impl.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/debug/trace_event.h"
@@ skipping 650 matching lines @@
   std::vector<DebugRect> new_paint_rects;
 
   for (size_t i = 0; i < debug_rects.size(); ++i) {
     SkColor stroke_color = 0;
     SkColor fill_color = 0;
     float stroke_width = 0.f;
     std::string label_text;
 
     switch (debug_rects[i].type) {
       case PAINT_RECT_TYPE:
+      case FIRST_PAINT_RECT_TYPE:
         new_paint_rects.push_back(debug_rects[i]);
         continue;
       case PROPERTY_CHANGED_RECT_TYPE:
         stroke_color = DebugColors::PropertyChangedRectBorderColor();
         fill_color = DebugColors::PropertyChangedRectFillColor();
         stroke_width = DebugColors::PropertyChangedRectBorderWidth();
         break;
       case SURFACE_DAMAGE_RECT_TYPE:
         stroke_color = DebugColors::SurfaceDamageRectBorderColor();
         fill_color = DebugColors::SurfaceDamageRectFillColor();
@@ skipping 60 matching lines @@
                   label_text);
   }
 
   if (new_paint_rects.size()) {
     paint_rects_.swap(new_paint_rects);
     fade_step_ = DebugColors::kFadeSteps;
   }
   if (fade_step_ > 0) {
     fade_step_--;
     for (size_t i = 0; i < paint_rects_.size(); ++i) {
-      DrawDebugRect(canvas,
-                    &paint,
-                    paint_rects_[i],
-                    DebugColors::PaintRectBorderColor(fade_step_),
-                    DebugColors::PaintRectFillColor(fade_step_),
-                    DebugColors::PaintRectBorderWidth(),
-                    "");
+      bool is_first_paint = paint_rects_[i].type == FIRST_PAINT_RECT_TYPE;
+      DrawDebugRect(
+          canvas,
+          &paint,
+          paint_rects_[i],
+          DebugColors::PaintRectBorderColor(fade_step_, is_first_paint),
+          DebugColors::PaintRectFillColor(fade_step_, is_first_paint),
+          DebugColors::PaintRectBorderWidth(),
+          "");
     }
   }
 }
 
 const char* HeadsUpDisplayLayerImpl::LayerTypeAsString() const {
   return "cc::HeadsUpDisplayLayerImpl";
 }
 
 void HeadsUpDisplayLayerImpl::AsValueInto(
     base::debug::TracedValue* dict) const {
   LayerImpl::AsValueInto(dict);
   dict->SetString("layer_name", "Heads Up Display Layer");
 }
 
 }  // namespace cc