media/filters/Gav1VideoDecoder: Fix a bug to block ReleaseBuffer

Bug: 1026522
Test: Play Gav1VideoDecoder for an hour
Change-Id: Ied41960243364ec3eea05fc2d7bde4fc945004c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2037273
Auto-Submit: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738240}

media/filters/gav1_video_decoder.cc

@@ -121,7 +121,7 @@ int ReleaseFrameBufferImpl(void* private_data,
                            Libgav1FrameBuffer* frame_buffer) {
   DCHECK(private_data);
   DCHECK(frame_buffer);
-  if (frame_buffer->private_data)
+  if (!frame_buffer->private_data)
     return -1;
   auto* pool = reinterpret_cast<FrameBufferPool*>(private_data);
   pool->ReleaseFrameBuffer(frame_buffer->private_data);