Make DETECT_IMPORTANT_CONTENT the default Plugins content setting based

chrome/test/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")
 import("//build/module_args/v8.gni")
 import("//testing/test.gni")
 
@@ skipping 666 matching lines @@
     # TODO(GYP) if (is_win) {
     #       ['incremental_chrome_dll==1', {
     #         'UseLibraryDependencyInputs': "true",
     # }
 
     if (cld_version == 0 || cld_version == 2) {
       # Because the browser_tests use translate, they need CLD data.
       deps += [ "//third_party/cld_2:cld2_platform_impl" ]
     }
 
+    if (enable_plugins) {
+      sources += chrome_tests_gypi_values.chrome_browser_tests_plugins_sources
+    }
     if (!enable_one_click_signin) {
       sources -= [ "../browser/ui/sync/one_click_signin_bubble_links_delegate_browsertest.cc" ]
     }
     if (enable_nacl) {
       sources += [
         "../browser/extensions/extension_nacl_browsertest.cc",
         "../browser/nacl_host/test/gdb_debug_stub_browsertest.cc",
       ]
       deps += [ "//components/nacl/renderer/plugin:nacl_trusted_plugin" ]
 
@@ skipping 1044 matching lines @@
       }
 
       if (cld_version == 0 || cld_version == 2) {
         # Use whatever CLD2 data access mode that the
         # application embedder is using.
         deps += [ "//third_party/cld_2:cld2_platform_impl" ]
       }
     }
   }
 }