Don't short-circuit MSE seeks in WebMediaPlayer impls

media/blink/webmediaplayer_impl.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 "media/blink/webmediaplayer_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 
@@ skipping 285 matching lines @@
 
   ReadyState old_state = ready_state_;
   if (ready_state_ > WebMediaPlayer::ReadyStateHaveMetadata)
     SetReadyState(WebMediaPlayer::ReadyStateHaveMetadata);
 
   base::TimeDelta new_seek_time = base::TimeDelta::FromSecondsD(seconds);
 
   if (seeking_) {
     if (new_seek_time == seek_time_) {
       if (chunk_demuxer_) {
-        if (!pending_seek_) {
-          // If using media source demuxer, only suppress redundant seeks if
-          // there is no pending seek. This enforces that any pending seek that
-          // results in a demuxer seek is preceded by matching
-          // CancelPendingSeek() and StartWaitingForSeek() calls.
-          return;
-        }
+        // Don't suppress any redundant in-progress MSE seek. There could have
+        // been changes to the underlying buffers after seeking the demuxer and
+        // before receiving OnPipelineSeeked() for the currently in-progress
+        // seek.
+        MEDIA_LOG(DEBUG, media_log_)
+            << "Detected MediaSource seek to same time as in-progress seek to "
+            << seek_time_ << ".";
       } else {
         // Suppress all redundant seeks if unrestricted by media source demuxer
         // API.
         pending_seek_ = false;
         pending_seek_time_ = base::TimeDelta();
         return;
       }
     }
 
     pending_seek_ = true;
     pending_seek_time_ = new_seek_time;
     if (chunk_demuxer_)
       chunk_demuxer_->CancelPendingSeek(pending_seek_time_);
     return;
   }
 
   media_log_->AddEvent(media_log_->CreateSeekEvent(seconds));
 
   // Update our paused time.
-  // In paused state ignore the seek operations to current time if the loading
-  // is completed and generate OnPipelineBufferingStateChanged event to
-  // eventually fire seeking and seeked events
+  // For non-MSE playbacks, in paused state ignore the seek operations to
+  // current time if the loading is completed and generate
+  // OnPipelineBufferingStateChanged event to eventually fire seeking and seeked
+  // events. We don't short-circuit MSE seeks in this logic because the
+  // underlying buffers around the seek time might have changed (or even been
+  // removed) since previous seek/preroll/pause action, and the pipeline might
+  // need to flush so the new buffers are decoded and rendered instead of the
+  // old ones.
   if (paused_) {
-    if (paused_time_ != new_seek_time) {
+    if (paused_time_ != new_seek_time || chunk_demuxer_) {
       paused_time_ = new_seek_time;
     } else if (old_state == ReadyStateHaveEnoughData) {
       main_task_runner_->PostTask(
           FROM_HERE,
           base::Bind(&WebMediaPlayerImpl::OnPipelineBufferingStateChanged,
                      AsWeakPtr(), BUFFERING_HAVE_ENOUGH));
       return;
     }
   }
 
@@ skipping 706 matching lines @@
 
   // pause() may be called after playback has ended and the HTMLMediaElement
   // requires that currentTime() == duration() after ending.  We want to ensure
   // |paused_time_| matches currentTime() in this case or a future seek() may
   // incorrectly discard what it thinks is a seek to the existing time.
   paused_time_ =
       ended_ ? pipeline_.GetMediaDuration() : pipeline_.GetMediaTime();
 }
 
 }  // namespace media