HUD: Show first paint invalidation in red

cc/debug/debug_rect_history.cc

Index: cc/debug/debug_rect_history.cc
diff --git a/cc/debug/debug_rect_history.cc b/cc/debug/debug_rect_history.cc
index e8792e7789e884451ffc7800d38741813fbf7021..97221d96c7e6e13e9f28ab3a4eb86945eabc851d 100644
--- a/cc/debug/debug_rect_history.cc
+++ b/cc/debug/debug_rect_history.cc
@@ -83,10 +83,11 @@ void DebugRectHistory::SavePaintRects(LayerImpl* layer) {
                          static_cast<float>(layer->bounds().height());
     gfx::Rect update_content_rect = gfx::ScaleToEnclosingRect(
         gfx::ToEnclosingRect(layer->update_rect()), width_scale, height_scale);
-    debug_rects_.push_back(
-        DebugRect(PAINT_RECT_TYPE,
-                  MathUtil::MapEnclosingClippedRect(
-                      layer->screen_space_transform(), update_content_rect)));
+    debug_rects_.push_back(DebugRect(
+        layer->includes_first_paint_invalidation() ? FIRST_PAINT_RECT_TYPE
+                                                   : PAINT_RECT_TYPE,
+        MathUtil::MapEnclosingClippedRect(layer->screen_space_transform(),
+                                          update_content_rect)));
   }
 
   for (unsigned i = 0; i < layer->children().size(); ++i)