Initialize media timeline correctly for positive start times.

media/base/pipeline.cc

 // Copyright (c) 2012 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/base/pipeline.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 325 matching lines @@
       return InitializeDemuxer(done_cb);
 
     case kInitRenderer:
       return InitializeRenderer(base::Bind(done_cb, PIPELINE_OK));
 
     case kPlaying:
       // Report metadata the first time we enter the playing state.
       if (!is_initialized_) {
         is_initialized_ = true;
         ReportMetadata();
+        start_timestamp_ = demuxer_->GetStartTime();
       }
 
       base::ResetAndReturn(&seek_cb_).Run(PIPELINE_OK);
 
+      DCHECK(start_timestamp_ >= base::TimeDelta());

[scherkus (not reviewing), 2014/09/16 00:16:51]

is it actually possible to craft such a file? if so, what happens in release
build? is this something we care about?

(IOW, DCHECK -> CHECK?)

[DaleCurtis, 2014/09/16 01:17:46]

I don't think it should be a CHECK, just a DCHECK. It's something that the API
contract says shouldn't be possible. It could only ever happen if Blink let
through a negative seek or GetStartTime() fails its contract.

       renderer_->StartPlayingFrom(start_timestamp_);
 
       if (text_renderer_)
         text_renderer_->StartPlaying();
 
       PlaybackRateChangedTask(GetPlaybackRate());
       VolumeChangedTask(GetVolume());
       return;
 
     case kStopping:
@@ skipping 217 matching lines @@
 
     // TODO(scherkus): should we run the callback?  I'm tempted to say the API
     // will only execute the first Seek() request.
     DVLOG(1) << "Media pipeline has not started, ignoring seek to "
              << time.InMicroseconds() << " (current state: " << state_ << ")";
     return;
   }
 
   DCHECK(seek_cb_.is_null());
 
+  const base::TimeDelta seek_timestamp =
+      std::max(time, demuxer_->GetStartTime());

[scherkus (not reviewing), 2014/09/16 00:07:31]

do we need to update pipeline_unittest.cc? IIRC we have a
StrictMock<MockDemuxer> and it'd be nice to have at least one test that verifies
we're using the right time

[DaleCurtis, 2014/09/16 01:17:46]

Done.

+
   SetState(kSeeking);
   seek_cb_ = seek_cb;
   renderer_ended_ = false;
   text_renderer_ended_ = false;
-  start_timestamp_ = time;
+  start_timestamp_ = seek_timestamp;
 
-  DoSeek(time,
+  DoSeek(seek_timestamp,
          base::Bind(&Pipeline::OnStateTransition, weak_factory_.GetWeakPtr()));
 }
 
 void Pipeline::OnRendererEnded() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   media_log_->AddEvent(media_log_->CreateEvent(MediaLogEvent::ENDED));
 
   if (state_ != kPlaying)
     return;
 
@@ skipping 103 matching lines @@
   metadata_cb_.Run(metadata);
 }
 
 void Pipeline::BufferingStateChanged(BufferingState new_buffering_state) {
   DVLOG(1) << __FUNCTION__ << "(" << new_buffering_state << ") ";
   DCHECK(task_runner_->BelongsToCurrentThread());
   buffering_state_cb_.Run(new_buffering_state);
 }
 
 }  // namespace media