Add a snapshot of flutter/engine/src/build to our sdk

build/linux/unbundle/ffmpeg.gyp

+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'targets': [
+    {
+      'target_name': 'ffmpeg',
+      'type': 'none',
+      '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',
+          'USE_SYSTEM_FFMPEG',
+        ],
+      },
+      'link_settings': {
+        'ldflags': [
+          '<!@(pkg-config --libs-only-L --libs-only-other libavcodec libavformat libavutil)',
+        ],
+        'libraries': [
+          '<!@(pkg-config --libs-only-l libavcodec libavformat libavutil)',
+        ],
+      },
+    },
+  ],
+}