Use base::Optional<int32_t> in H264POC::ComputePicOrderCnt(...)

media/video/h264_poc.h

 // 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.
 
 #ifndef MEDIA_VIDEO_H264_POC_H_
 #define MEDIA_VIDEO_H264_POC_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 
 namespace media {
 
 struct H264SPS;
 struct H264SliceHeader;
 
 class MEDIA_EXPORT H264POC {
  public:
   H264POC();
   ~H264POC();
 
-  // Compute the picture order count for a slice, storing the result into
-  // |*pic_order_cnt|.
-  // TODO(sandersd): Switch to a base::Optional<int32_t> return type.
-  bool ComputePicOrderCnt(
-      const H264SPS* sps,
-      const H264SliceHeader& slice_hdr,
-      int32_t* pic_order_cnt);
+  // Returns the picture order count for a slice.
+  base::Optional<int32_t> ComputePicOrderCnt(const H264SPS* sps,
+                                             const H264SliceHeader& slice_hdr);
 
   // As specified, the POC of a frame with MMCO5 changes (to zero) after
   // decoding. We instead return 0 immediately, and flag that this has occurred
   // by returning true here until ComputePicOrderCnt() is called again.
   //
   // Frames with MMCO5 do not reorder relative to frames earlier in decode
   // order, but may reorder relative to frames later in decode order (just like
   // IDRs).
   bool IsPendingMMCO5() { return pending_mmco5_; }
 
   // Reset computation state. It's best (although not strictly required) to call
   // this after a seek.
   void Reset();
 
  private:
   int32_t ref_pic_order_cnt_msb_;
   int32_t ref_pic_order_cnt_lsb_;
   int32_t prev_frame_num_;
   int32_t prev_frame_num_offset_;
   bool pending_mmco5_;
 
   DISALLOW_COPY_AND_ASSIGN(H264POC);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_H264_POC_H_