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 fcb2733aee90279959fff97e43148cba86413eb4..321c4306c2be2d50563bc6339a6c2c9ba0cdfef7 100644
--- a/cc/layers/heads_up_display_layer_impl.cc
+++ b/cc/layers/heads_up_display_layer_impl.cc
@@ -667,6 +667,7 @@ 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:
@@ -747,13 +748,15 @@ 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(),
+          "");
     }
   }
 }