Convert enable_plugins to a buildflag header.

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")
@@ skipping 261 matching lines @@
   allow_circular_includes_from = []
   defines = []
   public_deps = [
     "//ppapi/features",
   ]
   deps = [
     "//base/third_party/dynamic_annotations:dynamic_annotations",
     "//gpu",
     "//media:media_features",
     "//media:shared_memory_support",
+    "//ppapi/features",
     "//skia",
     "//third_party/libyuv",
     "//ui/events:events_base",
     "//url:url",
   ]
   libs = []
   configs += [ ":base_config" ]
 
   if (media_use_ffmpeg) {
     if (!is_android) {
@@ skipping 323 matching lines @@
 
 fuzzer_test("media_container_names_fuzzer") {
   sources = [
     "container_names_fuzzertest.cc",
   ]
   deps = [
     "//base",
     "//media",
   ]
 }