Restore swap to clear display item list visual rects.

cc/playback/display_item_list.cc

 // Copyright 2014 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/playback/display_item_list.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 100 matching lines @@
     inputs_.visual_rects[inputs_.begin_item_indices.back()].Union(visual_rect);
 }
 
 void DisplayItemList::Finalize() {
   TRACE_EVENT0("cc", "DisplayItemList::Finalize");
   DCHECK(inputs_.items.size() == inputs_.visual_rects.size())
       << "items.size() " << inputs_.items.size() << " visual_rects.size() "
       << inputs_.visual_rects.size();
   rtree_.Build(inputs_.visual_rects);
 
-  // TODO(wkorman): Restore the below, potentially with a switch to allow
-  // clearing visual rects except for Blimp engine. http://crbug.com/633750
-  // if (!retain_visual_rects_)
-  //   // This clears both the vector and the vector's capacity, since
-  //   // visual_rects won't be used anymore.
-  //   std::vector<gfx::Rect>().swap(inputs_.visual_rects);
+  if (!retain_visual_rects_)
+    // This clears both the vector and the vector's capacity, since
+    // visual_rects won't be used anymore.
+    std::vector<gfx::Rect>().swap(inputs_.visual_rects);
 }
 
 bool DisplayItemList::IsSuitableForGpuRasterization() const {
   // TODO(wkorman): This is more permissive than Picture's implementation, since
   // none of the items might individually trigger a veto even though they
   // collectively have enough "bad" operations that a corresponding Picture
   // would get vetoed. See crbug.com/513016.
   return inputs_.all_items_are_suitable_for_gpu_rasterization;
 }
 
 int DisplayItemList::ApproximateOpCount() const {
   return approximate_op_count_;
 }
 
 size_t DisplayItemList::ApproximateMemoryUsage() const {
   size_t memory_usage = sizeof(*this);
 
   size_t external_memory_usage = 0;
-  // Warning: this double-counts SkPicture data if use_cached_picture is
-  // also true.
   for (const auto& item : inputs_.items) {
     size_t bytes = 0;
     switch (item.type()) {
       case DisplayItem::CLIP:
         bytes = static_cast<const ClipDisplayItem&>(item).ExternalMemoryUsage();
         break;
       case DisplayItem::CLIP_PATH:
         bytes =
             static_cast<const ClipPathDisplayItem&>(item).ExternalMemoryUsage();
         break;
@@ skipping 82 matching lines @@
   TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug.display_items") ","
       TRACE_DISABLED_BY_DEFAULT("cc.debug.picture") ","
       TRACE_DISABLED_BY_DEFAULT("devtools.timeline.picture"),
       "cc::DisplayItemList", this,
       TracedDisplayItemList::AsTraceableDisplayItemList(this,
           DisplayItemsTracingEnabled()));
 }
 
 void DisplayItemList::GenerateDiscardableImagesMetadata() {
-  // This should be only called once, and only after CreateAndCacheSkPicture.
+  // This should be only called once.
   DCHECK(image_map_.empty());
 
   gfx::Rect bounds = rtree_.GetBounds();
   DiscardableImageMap::ScopedMetadataGenerator generator(
       &image_map_, gfx::Size(bounds.right(), bounds.bottom()));
   Raster(generator.canvas(), nullptr, gfx::Rect(), 1.f);
 }
 
 void DisplayItemList::GetDiscardableImagesInRect(
     const gfx::Rect& rect,
     float contents_scale,
     std::vector<DrawImage>* images) {
   image_map_.GetDiscardableImagesInRect(rect, contents_scale, images);
 }
 
 gfx::Rect DisplayItemList::GetRectForImage(ImageId image_id) const {
   return image_map_.GetRectForImage(image_id);
 }
 
 }  // namespace cc