Move enable extensions define to a build flag.

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("//extensions/features/features.gni")
 import("//tools/grit/grit_rule.gni")
 
 grit("resources") {
   source = "resources/renderer_resources.grd"
   defines = chrome_grit_defines
   use_qualified_include = true
   output_dir = "$root_gen_dir/chrome"
   output_name = "renderer_resources"
   outputs = [
     "grit/renderer_resources.h",
@@ skipping 91 matching lines @@
     "//components/subresource_filter/content/renderer",
     "//components/translate/content/renderer",
     "//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/capture",
     "//net",
     "//ppapi/features",
     "//printing/features",
     "//skia",
     "//storage/common",
     "//third_party/WebKit/public:blink",
     "//third_party/WebKit/public:image_resources",
     "//third_party/WebKit/public:resources",
@@ skipping 235 matching lines @@
     "chrome_mock_render_thread.h",
     "safe_browsing/mock_feature_extractor_clock.cc",
     "safe_browsing/mock_feature_extractor_clock.h",
     "safe_browsing/test_utils.cc",
     "safe_browsing/test_utils.h",
   ]
 
   deps = [
     ":renderer",
     "//content/test:test_support",
+    "//extensions/features",
     "//testing/gmock",
     "//testing/gtest",
   ]
 
   if (enable_print_preview) {
     deps += [ "//chrome/service" ]
   }
 
   if (enable_webrtc) {
     sources += [
       "media/mock_webrtc_logging_message_filter.cc",
       "media/mock_webrtc_logging_message_filter.h",
     ]
   }
 
   if (is_android) {
     sources -= [
       "safe_browsing/mock_feature_extractor_clock.cc",
       "safe_browsing/mock_feature_extractor_clock.h",
     ]
   }
 }