MSE: Cleanup WebM tracks parser initialization

media/formats/webm/webm_tracks_parser.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 "media/formats/webm/webm_tracks_parser.h"
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "media/base/media_util.h"
@@ skipping 29 matching lines @@
   mult /= timecode_scale_in_us;
   if (mult == 0)
     return kNoTimestamp();
 
   mult = static_cast<double>(mult) * timecode_scale_in_us;
   return base::TimeDelta::FromMicroseconds(mult);
 }
 
 WebMTracksParser::WebMTracksParser(const scoped_refptr<MediaLog>& media_log,
                                    bool ignore_text_tracks)
-    : track_type_(-1),
-      track_num_(-1),
-      seek_preroll_(-1),
-      codec_delay_(-1),
-      default_duration_(-1),
-      audio_track_num_(-1),
-      audio_default_duration_(-1),
-      video_track_num_(-1),
-      video_default_duration_(-1),
-      ignore_text_tracks_(ignore_text_tracks),
+    : ignore_text_tracks_(ignore_text_tracks),
       media_log_(media_log),
       audio_client_(media_log),
       video_client_(media_log) {
+  Reset();
 }
 
 WebMTracksParser::~WebMTracksParser() {}
 
-int WebMTracksParser::Parse(const uint8_t* buf, int size) {
-  track_type_ =-1;
-  track_num_ = -1;
-  default_duration_ = -1;
-  track_name_.clear();
-  track_language_.clear();
+void WebMTracksParser::Reset() {
+  ResetTrackEntry();
   audio_track_num_ = -1;
   audio_default_duration_ = -1;
   audio_decoder_config_ = AudioDecoderConfig();
   video_track_num_ = -1;
   video_default_duration_ = -1;
   video_decoder_config_ = VideoDecoderConfig();
   text_tracks_.clear();
   ignored_tracks_.clear();
   media_tracks_.reset(new MediaTracks());
+}
 
+void WebMTracksParser::ResetTrackEntry() {
+  track_type_ = -1;
+  track_num_ = -1;
+  track_name_.clear();
+  track_language_.clear();
+  codec_id_ = "";
+  codec_private_.clear();
+  seek_preroll_ = -1;
+  codec_delay_ = -1;
+  default_duration_ = -1;
+  audio_client_.Reset();
+  video_client_.Reset();
+}
+
+int WebMTracksParser::Parse(const uint8_t* buf, int size) {
   WebMListParser parser(kWebMIdTracks, this);

[wolenetz, 2016/03/28 20:45:07]

Note, this works without invoking Reset() here too because all users of this
class assume it's a one-shot deal and construct it each time. I could add
Reset() to top of ::Parse() with extra runtime cost, to make it more robust
against future usage change by callers. wdyt?

[wolenetz, 2016/03/28 20:53:44]

From quick chat, I've added usage of a flag here to track whether or not a
Reset() is needed.

   int result = parser.Parse(buf, size);
 
   if (result <= 0)
     return result;
 
   // For now we do all or nothing parsing.
   return parser.IsParsingComplete() ? result : 0;
 }
 
 base::TimeDelta WebMTracksParser::GetAudioDefaultDuration(
@@ skipping 10 matching lines @@
 
 WebMParserClient* WebMTracksParser::OnListStart(int id) {
   if (id == kWebMIdContentEncodings) {
     DCHECK(!track_content_encodings_client_.get());
     track_content_encodings_client_.reset(
         new WebMContentEncodingsClient(media_log_));
     return track_content_encodings_client_->OnListStart(id);
   }
 
   if (id == kWebMIdTrackEntry) {
-    track_type_ = -1;
-    track_num_ = -1;
-    default_duration_ = -1;
-    track_name_.clear();
-    track_language_.clear();
-    codec_id_ = "";
-    codec_private_.clear();
-    audio_client_.Reset();
-    video_client_.Reset();
+    ResetTrackEntry();
     return this;
   }
 
   if (id == kWebMIdAudio)
     return &audio_client_;
 
   if (id == kWebMIdVideo)
     return &video_client_;
 
   return this;
@@ skipping 222 matching lines @@
     } else {
       track_language_ = str;
     }
     return true;
   }
 
   return true;
 }
 
 }  // namespace media