HUD: Show first paint invalidation in red

cc/layers/heads_up_display_layer_impl.cc

Index: cc/layers/heads_up_display_layer_impl.cc
diff --git a/cc/layers/heads_up_display_layer_impl.cc b/cc/layers/heads_up_display_layer_impl.cc
index c46c1be1c6e3a705ab8ffcf256d328babd66ce22..c68d5f500e283bb945ab5cad7b0e29cab500798c 100644
--- a/cc/layers/heads_up_display_layer_impl.cc
+++ b/cc/layers/heads_up_display_layer_impl.cc
@@ -668,6 +668,7 @@ void HeadsUpDisplayLayerImpl::DrawDebugRects(
 
     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:
@@ -748,13 +749,15 @@ void HeadsUpDisplayLayerImpl::DrawDebugRects(
   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(),
+          "");
     }
   }
 }