HUD: Show first paint invalidation in red

cc/debug/debug_rect_history.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/debug/debug_rect_history.h"
 
 #include "cc/base/math_util.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/layer_utils.h"
@@ skipping 58 matching lines @@
   if (debug_state.show_layer_animation_bounds_rects)
     SaveLayerAnimationBoundsRects(render_surface_layer_list);
 }
 
 void DebugRectHistory::SavePaintRects(LayerImpl* layer) {
   // We would like to visualize where any layer's paint rect (update rect) has
   // changed, regardless of whether this layer is skipped for actual drawing or
   // not. Therefore we traverse recursively over all layers, not just the render
   // surface list.
 
-  if (!layer->update_rect().IsEmpty() && layer->DrawsContent()) {
+  if (layer->DrawsContent() && !layer->GetDetailedPaintRects(&debug_rects_) &&
+      !layer->update_rect().IsEmpty()) {
     float width_scale = layer->content_bounds().width() /
                         static_cast<float>(layer->bounds().width());
     float height_scale = layer->content_bounds().height() /
                          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)));
@@ skipping 195 matching lines @@
     debug_rects_.push_back(
         DebugRect(ANIMATION_BOUNDS_RECT_TYPE,
                   gfx::ToEnclosingRect(gfx::RectF(inflated_bounds.x(),
                                                   inflated_bounds.y(),
                                                   inflated_bounds.width(),
                                                   inflated_bounds.height()))));
   }
 }
 
 }  // namespace cc