cc: Implement RemoveLast for DisplayItemList.

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 <string>
 
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ skipping 141 matching lines @@
       // Warning: this double-counts SkPicture data if use_cached_picture_ is
       // also true.
       picture_memory_usage_ += item->picture_memory_usage();
     }
   }
 
   if (!retain_individual_display_items_)
     items_.clear();
 }
 
+void DisplayItemList::RemoveLast() {
+  // We cannot remove the last item if it has been squashed into a picture.
+  // The last item should not have been handled by ProcessAppendedItems, so we
+  // don't need to remove it from approximate_op_count_, etc.
+  DCHECK(retain_individual_display_items_);
+  DCHECK(!use_cached_picture_);
+  items_.RemoveLast();
+}
+
 void DisplayItemList::Finalize() {
   ProcessAppendedItems();
 
   if (use_cached_picture_) {
     // Convert to an SkPicture for faster rasterization.
     DCHECK(use_cached_picture_);
     DCHECK(!picture_);
     picture_ = skia::AdoptRef(recorder_->endRecordingAsPicture());
     DCHECK(picture_);
     picture_memory_usage_ +=
@@ skipping 76 matching lines @@
     return;
 
   pixel_refs_->GatherPixelRefsFromPicture(picture_.get());
 }
 
 void* DisplayItemList::GetSidecar(DisplayItem* display_item) {
   return items_.GetSidecar(display_item);
 }
 
 }  // namespace cc