HUD: Show first paint invalidation in red

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 37c83289700ab9fef4cd1fb356d0f9c354d29b0f..baa2d24117c0eb3eb4417e5ac396d8324a8b8d40 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -13,6 +13,7 @@
 #include "cc/base/math_util.h"
 #include "cc/base/util.h"
 #include "cc/debug/debug_colors.h"
+#include "cc/debug/debug_rect_history.h"
 #include "cc/debug/micro_benchmark_impl.h"
 #include "cc/debug/traced_value.h"
 #include "cc/layers/append_quads_data.h"
@@ -143,6 +144,8 @@ void PictureLayerImpl::PushPropertiesTo(LayerImpl* base_layer) {
   // in case push properties is skipped.
   layer_impl->invalidation_.Swap(&invalidation_);
   invalidation_.Clear();
+  layer_impl->debug_invalidation_.swap(debug_invalidation_);
+  debug_invalidation_.clear();
   needs_post_commit_initialization_ = true;
 
   // We always need to push properties.
@@ -1793,4 +1796,11 @@ size_t PictureLayerImpl::LayerEvictionTileIterator::CurrentTilingIndex() const {
   return 0;
 }
 
+bool PictureLayerImpl::GetDetailedPaintRects(std::vector<DebugRect>* rects) {
+  rects->insert(
+      rects->end(), debug_invalidation_.begin(), debug_invalidation_.end());
+  debug_invalidation_.clear();
+  return true;
+}
+
 }  // namespace cc