Convert USE_PROPRIETARY_CODECS to a buildflag header.

chrome/renderer/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/features.gni")
 import("//chrome/common/features.gni")
 import("//components/spellcheck/spellcheck_build_features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
@@ skipping 106 matching lines @@
     "//components/translate/core/common",
     "//components/translate/core/language_detection",
     "//components/visitedlink/renderer",
     "//components/web_cache/renderer",
     "//content/app/resources",
     "//content/app/strings",
     "//content/public/common",
     "//content/public/renderer",
     "//extensions/features",
     "//media",
+    "//media:media_features",
     "//media/capture",
     "//net",
     "//ppapi/features",
     "//printing/features",
     "//services/service_manager/public/cpp",
     "//skia",
     "//storage/common",
     "//third_party/WebKit/public:blink",
     "//third_party/WebKit/public:image_resources",
     "//third_party/WebKit/public:resources",
@@ skipping 260 matching lines @@
     ]
   }
 
   if (is_android) {
     sources -= [
       "safe_browsing/mock_feature_extractor_clock.cc",
       "safe_browsing/mock_feature_extractor_clock.h",
     ]
   }
 }