Make DETECT_IMPORTANT_CONTENT the default Plugins content setting based

components/content_settings/core/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.
 
 static_library("browser") {
   sources = [
     "content_settings_binary_value_map.cc",
     "content_settings_binary_value_map.h",
     "content_settings_client.h",
     "content_settings_default_provider.cc",
@@ skipping 16 matching lines @@
     "content_settings_provider.h",
     "content_settings_rule.cc",
     "content_settings_rule.h",
     "content_settings_usages_state.cc",
     "content_settings_usages_state.h",
     "content_settings_utils.cc",
     "content_settings_utils.h",
     "host_content_settings_map.cc",
     "host_content_settings_map.h",
     "local_shared_objects_counter.h",
+    "plugins_field_trial.cc",
+    "plugins_field_trial.h",
   ]
 
   deps = [
     "//base",
     "//base:prefs",
     "//components/content_settings/core/common",
     "//components/pref_registry:pref_registry",
     "//net",
     "//url",
   ]
 
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "content_settings_mock_provider.cc",
     "content_settings_mock_provider.h",
     "content_settings_provider_unittest.cc",
     "content_settings_rule_unittest.cc",
     "content_settings_utils_unittest.cc",
+    "plugins_field_trial_unittest.cc",
   ]
 
   deps = [
     ":browser",
     "//base",
     "//components/content_settings/core/common",
     "//components/content_settings/core/test:test_support",
     "//testing/gtest",
     "//url",
   ]
 }