[C++11 Allowed Features] Declares a type-safe null pointer converting from NULL to nullptr in src/…

cc/resources/picture_pile_base.cc

 // Copyright 2013 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/resources/picture_pile_base.h"
 
 #include <algorithm>
 #include <set>
 #include <vector>
 
@@ skipping 207 matching lines @@
 
   invalidation_history_ <<= (frame_number - last_frame_number_);
   last_frame_number_ = frame_number;
 }
 
 bool PicturePileBase::PictureInfo::Invalidate(int frame_number) {
   AdvanceInvalidationHistory(frame_number);
   invalidation_history_.set(0);
 
   bool did_invalidate = !!picture_.get();
-  picture_ = NULL;
+  picture_ = nullptr;
   return did_invalidate;
 }
 
 bool PicturePileBase::PictureInfo::NeedsRecording(int frame_number,
                                                   int distance_to_visible) {
   AdvanceInvalidationHistory(frame_number);
 
   // We only need recording if we don't have a picture. Furthermore, we only
   // need a recording if we're within frequent invalidation distance threshold
   // or the invalidation is not frequent enough (below invalidation frequency
@@ skipping 10 matching lines @@
 const Picture* PicturePileBase::PictureInfo::GetPicture() const {
   return picture_.get();
 }
 
 float PicturePileBase::PictureInfo::GetInvalidationFrequency() const {
   return invalidation_history_.count() /
          static_cast<float>(INVALIDATION_FRAMES_TRACKED);
 }
 
 }  // namespace cc