Remove use_system_ffmpeg-related logic from media and other mainline gyp files.

build/linux/unbundle/ffmpeg.gyp

Index: build/linux/unbundle/ffmpeg.gyp
diff --git a/build/linux/unbundle/ffmpeg.gyp b/build/linux/unbundle/ffmpeg.gyp
index dfaaf0aee83668764b07c97846a035c933c4110d..e3c3723894ceae651920154dbb65cf83aa4d3d40 100644
--- a/build/linux/unbundle/ffmpeg.gyp
+++ b/build/linux/unbundle/ffmpeg.gyp
@@ -10,6 +10,31 @@
       'direct_dependent_settings': {
         'cflags': [
           '<!@(pkg-config --cflags libavcodec libavformat libavutil)',
+
+          '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
+              '--code "#define __STDC_CONSTANT_MACROS\n'
+              '#include <libavcodec/avcodec.h>\n'
+              'int test() { return AV_CODEC_ID_OPUS; }" '
+              '--on-failure -DCHROMIUM_OMIT_AV_CODEC_ID_OPUS=1)',
+
+          '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
+              '--code "#define __STDC_CONSTANT_MACROS\n'
+              '#include <libavcodec/avcodec.h>\n'
+              'int test() { return AV_CODEC_ID_VP9; }" '
+              '--on-failure -DCHROMIUM_OMIT_AV_CODEC_ID_VP9=1)',
+
+          '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
+              '--code "#define __STDC_CONSTANT_MACROS\n'
+              '#include <libavcodec/avcodec.h>\n'
+              'int test() { return AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL; }" '
+              '--on-failure -DCHROMIUM_OMIT_AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL=1)',
+
+          '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
+              '--code "#define __STDC_CONSTANT_MACROS\n'
+              '#include <libavcodec/avcodec.h>\n'
+              'int test() { struct AVFrame frame;\n'
+              'return av_frame_get_channels(&frame); }" '
+              '--on-failure -DCHROMIUM_NO_AVFRAME_CHANNELS=1)',
         ],
         'defines': [
           '__STDC_CONSTANT_MACROS',