Convert USE_PROPRIETARY_CODECS to a buildflag header.

media/filters/gpu_video_decoder.cc

Index: media/filters/gpu_video_decoder.cc
diff --git a/media/filters/gpu_video_decoder.cc b/media/filters/gpu_video_decoder.cc
index 723c6da03b6bb0becb79a26ce75f7d64c9be2aae..53d0de8a34e0bf3d1c7da23a2f98935a27a2c0c4 100644
--- a/media/filters/gpu_video_decoder.cc
+++ b/media/filters/gpu_video_decoder.cc
@@ -29,10 +29,11 @@
 #include "media/base/pipeline_status.h"
 #include "media/base/surface_manager.h"
 #include "media/base/video_decoder_config.h"
+#include "media/media_features.h"
 #include "media/renderers/gpu_video_accelerator_factories.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
-#if defined(USE_PROPRIETARY_CODECS)
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
 #include "media/formats/mp4/box_definitions.h"
 #endif
 
@@ -47,7 +48,7 @@ namespace {
 // be on the beefy side.
 static const size_t kSharedMemorySegmentBytes = 100 << 10;
 
-#if defined(OS_ANDROID) && defined(USE_PROPRIETARY_CODECS)
+#if defined(OS_ANDROID) && BUILDFLAG(USE_PROPRIETARY_CODECS)
 // Extract the SPS and PPS lists from |extra_data|. Each SPS and PPS is prefixed
 // with 0x0001, the Annex B framing bytes. The out parameters are not modified
 // on failure.
@@ -362,7 +363,7 @@ void GpuVideoDecoder::CompleteInitialization(int surface_id) {
   vda_config.is_deferred_initialization_allowed = true;
   vda_config.initial_expected_coded_size = config_.coded_size();
 
-#if defined(OS_ANDROID) && defined(USE_PROPRIETARY_CODECS)
+#if defined(OS_ANDROID) && BUILDFLAG(USE_PROPRIETARY_CODECS)
   // We pass the SPS and PPS on Android because it lets us initialize
   // MediaCodec more reliably (http://crbug.com/649185).
   if (config_.codec() == kCodecH264)