Make FFmpegVideoDecoder defer a flush until the pending read completes.

media/filters/ffmpeg_video_decoder.cc

Index: media/filters/ffmpeg_video_decoder.cc
diff --git a/media/filters/ffmpeg_video_decoder.cc b/media/filters/ffmpeg_video_decoder.cc
index f5eb500fa74d449c54f4fc417d553e7deb44ac37..3d382648e9598c1a755b26eed53df515359a7e6c 100644
--- a/media/filters/ffmpeg_video_decoder.cc
+++ b/media/filters/ffmpeg_video_decoder.cc
@@ -163,9 +163,22 @@ void FFmpegVideoDecoder::Flush(const base::Closure& callback) {
     return;
   }
 
+  flush_cb_ = callback;
+
+  // Defer the flush if a read is pending.
+  if (!read_cb_.is_null())
+    return;
+
+  DoFlush();
+}
+
+void FFmpegVideoDecoder::DoFlush() {
+  DCHECK(read_cb_.is_null());
+
   avcodec_flush_buffers(codec_context_);
   state_ = kNormal;
-  callback.Run();
+  flush_cb_.Run();
+  flush_cb_.Reset();
 }
 
 void FFmpegVideoDecoder::Read(const ReadCB& read_cb) {
@@ -226,6 +239,12 @@ void FFmpegVideoDecoder::DoDecodeBuffer(const scoped_refptr<Buffer>& buffer) {
     return;
   }
 
+  if (!flush_cb_.is_null()) {
+    DeliverFrame(NULL);
+    DoFlush();
+    return;
+  }
+
   // During decode, because reads are issued asynchronously, it is possible to
   // receive multiple end of stream buffers since each read is acked. When the
   // first end of stream buffer is read, FFmpeg may still have frames queued