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

webrtc/api/rtcstatscollector_unittest.cc

 /*
  *  Copyright 2016 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.
  */
 
-#include "webrtc/stats/rtcstatscollector.h"
+#include "webrtc/api/rtcstatscollector.h"
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "webrtc/api/jsepsessiondescription.h"
 #include "webrtc/api/rtcstats_objects.h"
 #include "webrtc/api/rtcstatsreport.h"
 #include "webrtc/api/test/mock_datachannel.h"
 #include "webrtc/api/test/mock_peerconnection.h"
@@ skipping 352 matching lines @@
   rtc::scoped_refptr<FakeRTCStatsCollector> collector_;
 };
 
 TEST_F(RTCStatsCollectorTestWithFakeCollector, ThreadUsageAndResultsMerging) {
   collector_->VerifyThreadUsageAndResultsMerging();
 }
 
 }  // namespace
 
 }  // namespace webrtc