Always enqueue an empty buffer when flush

media/gpu/v4l2_slice_video_decode_accelerator.cc

 // Copyright 2015 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/gpu/v4l2_slice_video_decode_accelerator.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/videodev2.h>
 #include <poll.h>
@@ skipping 1820 matching lines @@
 
   decoder_thread_task_runner_->PostTask(
       FROM_HERE, base::Bind(&V4L2SliceVideoDecodeAccelerator::FlushTask,
                             base::Unretained(this)));
 }
 
 void V4L2SliceVideoDecodeAccelerator::FlushTask() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
-  if (!decoder_input_queue_.empty()) {
-    // We are not done with pending inputs, so queue an empty buffer,
-    // which - when reached - will trigger flush sequence.
-    decoder_input_queue_.push(
-        linked_ptr<BitstreamBufferRef>(new BitstreamBufferRef(
-            decode_client_, decode_task_runner_, nullptr, kFlushBufferId)));
-    return;
-  }
-
-  // No more inputs pending, so just finish flushing here.
-  InitiateFlush();
+  // We are not done with pending inputs, so queue an empty buffer,

[Owen Lin, 2016/06/17 15:57:47]

Please also update the comment, how about:
Queue an empty buffer will trigger flush sequence after we are done with all
pending inputs.

[Pawel Osciak, 2016/06/20 00:55:53]

We actually may be done with pending inputs here already. Since the if() is
being removed, instead of checking if inputs are pending and queuing an empty
buffer only if they are, we unconditionally queue one.

How about:

"Queue an empty buffer which - when reached - will trigger the flush sequence."

[henryhsu, 2016/06/20 02:58:05]

Done.

+  // which - when reached - will trigger flush sequence.
+  decoder_input_queue_.push(
+      linked_ptr<BitstreamBufferRef>(new BitstreamBufferRef(
+          decode_client_, decode_task_runner_, nullptr, kFlushBufferId)));
+  return;

[kcwu, 2016/06/17 12:17:49]

delete this line

[Owen Lin, 2016/06/17 13:35:42]

Add one line in the end:
ScheduleDecodeBufferTaskIfNeeded()

[henryhsu, 2016/06/20 02:58:05]

Done.

[henryhsu, 2016/06/20 02:58:05]

Done.

 }
 
 void V4L2SliceVideoDecodeAccelerator::InitiateFlush() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
   // This will trigger output for all remaining surfaces in the decoder.
   // However, not all of them may be decoded yet (they would be queued
   // in hardware then).
   if (!decoder_->Flush()) {
@@ skipping 943 matching lines @@
 V4L2SliceVideoDecodeAccelerator::GetSupportedProfiles() {
   scoped_refptr<V4L2Device> device = V4L2Device::Create(V4L2Device::kDecoder);
   if (!device)
     return SupportedProfiles();
 
   return device->GetSupportedDecodeProfiles(arraysize(supported_input_fourccs_),
                                             supported_input_fourccs_);
 }
 
 }  // namespace media