Add BUILD.gn for //media/ffmpeg

media/base/BUILD.gn

 # Copyright 2014 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("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//media/media_options.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 
 source_set("base") {
   # This is part of the media component.
-  visibility = [
-    ":*",
-    "//media",
-    "//media/capture",
-  ]
+  visibility = [ "//media/*" ]
   sources = [
     "audio_block_fifo.cc",
     "audio_block_fifo.h",
     "audio_buffer.cc",
     "audio_buffer.h",
     "audio_buffer_converter.cc",
     "audio_buffer_converter.h",
     "audio_buffer_queue.cc",
     "audio_buffer_queue.h",
     "audio_capturer_source.h",
@@ skipping 567 matching lines @@
 
 fuzzer_test("media_container_names_fuzzer") {
   sources = [
     "container_names_fuzzertest.cc",
   ]
   deps = [
     "//base",
     "//media",
   ]
 }