Moving webrtc/stats/ into webrtc/api/ to resolve a circular dependency

webrtc/api/api.gyp

 # Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 139 matching lines @@
         'peerconnection.cc',
         'peerconnection.h',
         'peerconnectionfactory.cc',
         'peerconnectionfactory.h',
         'peerconnectionfactoryproxy.h',
         'peerconnectioninterface.h',
         'peerconnectionproxy.h',
         'proxy.h',
         'remoteaudiosource.cc',
         'remoteaudiosource.h',
+        'rtcstats.cc',
         'rtcstats.h',
+        'rtcstats_objects.cc',
         'rtcstats_objects.h',
+        'rtcstatscollector.cc',
+        'rtcstatscollector.h',
+        'rtcstatsreport.cc',
         'rtcstatsreport.h',
         'rtpparameters.h',
         'rtpreceiver.cc',
         'rtpreceiver.h',
         'rtpreceiverinterface.h',
         'rtpsender.cc',
         'rtpsender.h',
         'rtpsenderinterface.h',
         'sctputils.cc',
         'sctputils.h',
@@ skipping 40 matching lines @@
             'quicdatatransport.h',
           ],
           'export_dependent_settings': [
             '<(DEPTH)/third_party/libquic/libquic.gyp:libquic',
           ],
         }],
       ],
     },  # target libjingle_peerconnection
   ],  # targets
 }