Add BUILD.gn for //media/ffmpeg

media/ffmpeg/BUILD.gn

+# Copyright 2016 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.
+
+import("//media/media_options.gni")
+
+assert(media_use_ffmpeg)
+
+source_set("ffmpeg") {
+  visibility = [ "//media/*" ]
+  allow_circular_includes_from = [ "//media/base" ]
+  configs += [ "//media/base:base_config" ]
+  sources = [
+    "ffmpeg_common.cc",
+    "ffmpeg_common.h",
+    "ffmpeg_deleters.h",
+  ]
+  deps = [
+    "//base",
+    "//media:media_features",
+    "//media:shared_memory_support",
+    "//media/base",
+    "//third_party/ffmpeg",
+  ]
+}
+
+source_set("ffmpeg_unittests") {
+  testonly = true
+  sources = [
+    "ffmpeg_common_unittest.cc",
+  ]
+  deps = [
+    "//base",
+    "//media",
+    "//media/base:test_support",
+    "//testing/gtest",
+    "//third_party/ffmpeg",
+  ]
+}
+
+source_set("ffmpeg_regression_tests") {
+  testonly = true
+  sources = [
+    "ffmpeg_regression_tests.cc",
+  ]
+  deps = [
+    "//base",
+    "//media",
+    "//media/test:pipeline_integration_test_base",
+    "//testing/gmock",
+    "//third_party/ffmpeg",
+  ]
+}