Fix ChunkDemuxer seek deadlock

media/filters/video_renderer_base.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 "base/bind.h"
 #include "base/callback.h"
 #include "base/threading/platform_thread.h"
 #include "media/base/buffers.h"
 #include "media/base/filter_host.h"
 #include "media/base/limits.h"
@@ skipping 318 matching lines @@
   // frame when this is true.
   frame_available_.Signal();
   if (state_ == kFlushing) {
     AttemptFlush_Locked();
   } else if (state_ == kError || state_ == kStopped) {
     DoStopOrError_Locked();
   }
 }
 
 void VideoRendererBase::FrameReady(scoped_refptr<VideoFrame> frame) {
-  DCHECK(frame);
-
   base::AutoLock auto_lock(lock_);
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kStopped);
   DCHECK_NE(state_, kError);
   DCHECK_NE(state_, kFlushed);
   CHECK(pending_read_);
 
   pending_read_ = false;
 
   if (state_ == kFlushing) {
     AttemptFlush_Locked();
     return;
   }
 
+  if (!frame) {

[Ami GONE FROM CHROMIUM, 2012/01/29 22:12:38]

I thought this test encompassed the entire remainder of the function.  But now I
see that's not the case.  Is it really correct to not look at the ready_frames
in this case?

[acolwell GONE FROM CHROMIUM, 2012/01/30 00:14:14]

I believe so. Getting a NULL frame means that the demuxer has no more data to
give and continuing to ask will only give you more NULL responses. This means
that we will never exit a seek. The NULL frames are triggered by a new seek
requested at the WebMediaPlayerImpl level so finishing out a preroll wouldn't do
us any good because all the data will be immediately flushed anyways.

Added a comment indicating why we are early terminating the seek.

+    if (state_ != kSeeking)
+      return;
+
+    state_ = kPrerolled;
+    ResetAndRunCB(&seek_cb_, PIPELINE_OK);
+    return;
+  }
+
   // Discard frames until we reach our desired seek timestamp.
   if (state_ == kSeeking && !frame->IsEndOfStream() &&
       (frame->GetTimestamp() + frame->GetDuration()) <= seek_timestamp_) {
     AttemptRead_Locked();
     return;
   }
 
   // Adjust the incoming frame if its rendering stop time is past the duration
   // of the video itself. This is typically the last frame of the video and
   // occurs if the container specifies a duration that isn't a multiple of the
@@ skipping 105 matching lines @@
 
 int VideoRendererBase::NumFrames_Locked() const {
   lock_.AssertAcquired();
   int outstanding_frames =
       (current_frame_ ? 1 : 0) + (last_available_frame_ ? 1 : 0) +
       (current_frame_ && (current_frame_ == last_available_frame_) ? -1 : 0);
   return ready_frames_.size() + outstanding_frames;
 }
 
 }  // namespace media