Re-land first pass BackgroundTracingManager.

content/content_tests.gypi

 # Copyright (c) 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': {
     'layouttest_support_content_sources': [
       'public/test/layouttest_support.h',
       'public/test/nested_message_pump_android.cc',
       'public/test/nested_message_pump_android.h',
@@ skipping 223 matching lines @@
       'browser/renderer_host/render_process_host_browsertest.cc',
       'browser/renderer_host/render_view_host_browsertest.cc',
       'browser/renderer_host/render_widget_host_view_browsertest.cc',
       'browser/screen_orientation/screen_orientation_browsertest.cc',
       'browser/security_exploit_browsertest.cc',
       'browser/service_worker/service_worker_browsertest.cc',
       'browser/session_history_browsertest.cc',
       'browser/shared_worker/worker_browsertest.cc',
       'browser/site_per_process_browsertest.cc',
       'browser/site_per_process_browsertest.h',
+      'browser/tracing/background_tracing_manager_browsertest.cc',
       'browser/tracing/tracing_controller_browsertest.cc',
       'browser/transition_browsertest.cc',
       'browser/web_contents/opened_by_dom_browsertest.cc',
       'browser/web_contents/touch_editable_impl_aura_browsertest.cc',
       'browser/web_contents/web_contents_impl_browsertest.cc',
       'browser/web_contents/web_contents_view_aura_browsertest.cc',
       'browser/webkit_browsertest.cc',
       'browser/webui/web_ui_mojo_browsertest.cc',
       'child/site_isolation_policy_browsertest.cc',
       'child/child_discardable_shared_memory_manager_browsertest.cc',
@@ skipping 1896 matching lines @@
                   'files': ['<(PRODUCT_DIR)/libnpapi_test_plugin.so'],
                 },
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }