Use ffmpeg_features buildflags

media/ffmpeg/ffmpeg_common.h

Index: media/ffmpeg/ffmpeg_common.h
diff --git a/media/ffmpeg/ffmpeg_common.h b/media/ffmpeg/ffmpeg_common.h
index f2508bedcbf3621dc7985dc3be04b94a3e7049a6..21fa8daec97425f61f2ef079f1880ce3fabbb768 100644
--- a/media/ffmpeg/ffmpeg_common.h
+++ b/media/ffmpeg/ffmpeg_common.h
@@ -20,15 +20,16 @@
 #include "media/base/video_codecs.h"
 #include "media/base/video_frame.h"
 #include "media/ffmpeg/ffmpeg_deleters.h"
+#include "third_party/ffmpeg/ffmpeg_features.h"
 
 // Include FFmpeg header files.
 extern "C" {
-#if !defined(USE_SYSTEM_FFMPEG)
+#if !BUILDFLAG(USE_SYSTEM_FFMPEG)
 // Disable deprecated features which result in spammy compile warnings.  This
 // list of defines must mirror those in the 'defines' section of FFmpeg's
 // BUILD.gn file or the headers below will generate different structures!
 #define FF_API_CONVERGENCE_DURATION 0
-#endif  // !defined(USE_SYSTEM_FFMPEG)
+#endif  // !BUILDFLAG(USE_SYSTEM_FFMPEG)
 // Upstream libavcodec/utils.c still uses the deprecated
 // av_dup_packet(), causing deprecation warnings.
 // The normal fix for such things is to disable the feature as below,
@@ -42,9 +43,9 @@ extern "C" {
 MSVC_PUSH_DISABLE_WARNING(4244);
 #include <libavcodec/avcodec.h>
 #include <libavformat/avformat.h>
-#if !defined(USE_SYSTEM_FFMPEG)
+#if !BUILDFLAG(USE_SYSTEM_FFMPEG)
 #include <libavformat/internal.h>
-#endif  // !defined(USE_SYSTEM_FFMPEG)
+#endif  // !BUILDFLAG(USE_SYSTEM_FFMPEG)
 #include <libavformat/avio.h>
 #include <libavutil/avutil.h>
 #include <libavutil/imgutils.h>