Convert USE_PROPRIETARY_CODECS to a buildflag header.

media/filters/ffmpeg_demuxer_unittest.cc

Index: media/filters/ffmpeg_demuxer_unittest.cc
diff --git a/media/filters/ffmpeg_demuxer_unittest.cc b/media/filters/ffmpeg_demuxer_unittest.cc
index 35bb7daa72da6ff11312dcec1aa8d54f7f6c34da..6699a93b1c28eceeac8e7e56b6a72ee0e18254db 100644
--- a/media/filters/ffmpeg_demuxer_unittest.cc
+++ b/media/filters/ffmpeg_demuxer_unittest.cc
@@ -1026,7 +1026,7 @@ TEST_F(FFmpegDemuxerTest, SeekWithCuesBeforeFirstCluster) {
   base::RunLoop().Run();
 }
 
-#if defined(USE_PROPRIETARY_CODECS)
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
 // Ensure ID3v1 tag reading is disabled.  id3_test.mp3 has an ID3v1 tag with the
 // field "title" set to "sample for id3 test".
 TEST_F(FFmpegDemuxerTest, NoID3TagData) {
@@ -1036,7 +1036,7 @@ TEST_F(FFmpegDemuxerTest, NoID3TagData) {
 }
 #endif
 
-#if defined(USE_PROPRIETARY_CODECS)
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
 // Ensure MP3 files with large image/video based ID3 tags demux okay.  FFmpeg
 // will hand us a video stream to the data which will likely be in a format we
 // don't accept as video; e.g. PNG.
@@ -1072,7 +1072,7 @@ TEST_F(FFmpegDemuxerTest, UnsupportedVideoSupportedAudioDemux) {
   EXPECT_TRUE(demuxer_->GetStream(DemuxerStream::AUDIO));
 }
 
-#if defined(USE_PROPRIETARY_CODECS)
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
 // FFmpeg returns null data pointers when samples have zero size, leading to
 // mistakenly creating end of stream buffers http://crbug.com/169133
 TEST_F(FFmpegDemuxerTest, MP4_ZeroStszEntry) {
@@ -1352,7 +1352,7 @@ TEST_F(FFmpegDemuxerTest, Read_Mp4_Crbug657437) {
   InitializeDemuxer();
 }
 
-#endif  // defined(USE_PROPRIETARY_CODECS)
+#endif  // BUILDFLAG(USE_PROPRIETARY_CODECS)
 
 TEST_F(FFmpegDemuxerTest, Read_Webm_Multiple_Tracks) {
   CreateDemuxer("multitrack-3video-2audio.webm");