extract content_browsertest WebRtcConstraintsBrowserTest into its own file

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 292 matching lines @@
     'content_browsertests_android_sources': [
       'browser/accessibility/android_granularity_movement_browsertest.cc',
       'browser/media/session/media_session_delegate_android_browsertest.cc',
       'shell/android/browsertests_apk/content_browser_tests_jni_onload.cc',
     ],
     'content_browsertests_webrtc_sources': [
       'browser/webrtc/webrtc_audio_browsertest.cc',
       'browser/webrtc/webrtc_audio_debug_recordings_browsertest.cc',
       'browser/webrtc/webrtc_browsertest.cc',
       'browser/webrtc/webrtc_capture_from_element_browsertest.cc',
+      'browser/webrtc/webrtc_constraints_browsertest.cc',
       'browser/webrtc/webrtc_content_browsertest_base.cc',
       'browser/webrtc/webrtc_content_browsertest_base.h',
       'browser/webrtc/webrtc_data_browsertest.cc',
       'browser/webrtc/webrtc_datachannel_browsertest.cc',
       'browser/webrtc/webrtc_getusermedia_browsertest.cc',
       'browser/webrtc/webrtc_image_capture_browsertest.cc',
       'browser/webrtc/webrtc_internals_browsertest.cc',
       'browser/webrtc/webrtc_ip_permissions_browsertest.cc',
       'browser/webrtc/webrtc_media_recorder_browsertest.cc',
       'browser/webrtc/webrtc_webcam_browsertest.cc',
@@ skipping 1602 matching lines @@
                   'content_unittests_apk.isolate',
                 ],
               },
             ],
           },
         ],
       ],
     }],
   ],
 }