Make DETECT_IMPORTANT_CONTENT the default Plugins content setting based

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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.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.
@@ skipping 226 matching lines @@
       "//components/app_modal",
       "//components/autofill/content/browser",
       "//components/browsing_data",
       "//components/data_reduction_proxy/content/browser",
       "//components/dom_distiller/content",
       "//components/favicon/content",
       "//components/history/content/browser",
       "//components/keyed_service/content",
       "//components/navigation_interception",
       "//components/password_manager/content/browser",
+      "//components/plugins/common",
       "//components/precache/content",
       "//components/sessions:sessions_content",
       "//components/storage_monitor",
       "//components/translate/content/browser",
       "//components/url_matcher",
       "//components/visitedlink/browser",
       "//components/visitedlink/common",
       "//components/web_cache/browser",
       "//components/web_modal",
       "//content/app/resources",
@@ skipping 867 matching lines @@
     ]
   }
 
   if (enable_wifi_bootstrapping) {
     sources += [
       "local_discovery/wifi/mock_wifi_manager.cc",
       "local_discovery/wifi/mock_wifi_manager.h",
     ]
   }
 }