Make DETECT_IMPORTANT_CONTENT the default Plugins content setting based

chrome/chrome_tests.gypi

 # Copyright 2013 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.
 {
   'variables': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 557 matching lines @@
       'test/data/webui/history_ui_browsertest.cc',
       'test/data/webui/history_ui_browsertest.h',
       'test/data/webui/ntp4_browsertest.cc',
       'test/data/webui/ntp4_browsertest.h',
       'test/data/webui/print_preview.cc',
       'test/data/webui/print_preview.h',
       'test/data/webui/webui_resource_browsertest.cc',
       'test/gpu/webgl_infobar_browsertest.cc',
       'test/ppapi/ppapi_browsertest.cc',
     ],
+    'chrome_browser_tests_plugins_sources': [
+      'browser/plugins/plugins_field_trial_browsertest.cc',
+    ],
     # Cross-platform views browser tests ready for toolkit-views on Mac.
     'chrome_browser_tests_views_sources': [
       'browser/ui/views/extensions/extension_uninstall_dialog_view_browsertest.cc',
       'browser/ui/views/frame/browser_non_client_frame_view_ash_browsertest.cc',
       'browser/ui/views/frame/browser_window_property_manager_browsertest_win.cc',
       'browser/ui/views/select_file_dialog_extension_browsertest.cc',
     ],
     # Cross-platform (except Mac) views browser tests. Assumes app list is
     # enabled (as for chrome_browser_ui_views_non_mac_sources).
     'chrome_browser_tests_views_non_mac_sources': [
@@ skipping 1474 matching lines @@
         ['enable_one_click_signin==0', {
           'sources!': [
             'browser/ui/sync/one_click_signin_bubble_links_delegate_browsertest.cc',
           ]
         }],
         ['enable_autofill_dialog==0', {
           'sources!': [
             'browser/ui/autofill/autofill_dialog_controller_browsertest.cc',
           ]
         }],
+        ['enable_plugins==1', {
+          'sources': [
+            '<@(chrome_browser_tests_plugins_sources)',
+          ],
+        }],
         ['disable_nacl==0', {
           'sources':[
             'browser/extensions/extension_nacl_browsertest.cc',
             'browser/nacl_host/test/gdb_debug_stub_browsertest.cc',
           ],
           'conditions': [
             ['disable_nacl_untrusted==0', {
               'sources': [
                 'test/nacl/nacl_browsertest.cc',
                 'test/nacl/nacl_browsertest_uma.cc',
@@ skipping 1143 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }