Move ENABLE_PEPPER_CDMS to a buildflag header.

chrome/browser/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/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
 import("//components/os_crypt/features.gni")
 import("//media/media_options.gni")
 import("//third_party/protobuf/proto_library.gni")
+import("//third_party/widevine/cdm/widevine.gni")
 
 # //build/config/android/rules.gni imports //tools/grit/grit_rule.gni, which
 # produces a conflict for the "grit" template so we have to only include one.
 if (is_android) {
   import("//build/config/android/rules.gni")
 } else {
   import("//tools/grit/grit_rule.gni")
 }
 
 additional_modules_list_file =
@@ skipping 1414 matching lines @@
     "//third_party/kasko",
     "//third_party/leveldatabase",
     "//third_party/libaddressinput",
     "//third_party/libjingle",
     "//third_party/libxml",
     "//third_party/libyuv",
     "//third_party/re2",
     "//third_party/smhasher:cityhash",
     "//third_party/webrtc/modules/desktop_capture",
     "//third_party/widevine/cdm:version_h",
+    "//third_party/widevine/cdm:cdm_features",
     "//third_party/zlib",
     "//third_party/zlib:compression_utils",
     "//third_party/zlib:minizip",
     "//third_party/zlib:zip",
     "//ui/base",
     "//ui/base:ui_data_pack",
     "//ui/base/ime",
     "//ui/events:events_base",
     "//ui/gfx",
     "//ui/gfx/geometry",
@@ skipping 2828 matching lines @@
   # linking all of the test support.
   static_library("pepper_cdm_test_constants") {
     testonly = true
     visibility = [ "//chrome/*" ]
     sources = [
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }