Wire up BWE stats through WebrtcSession so that they are filled in both for audio and video calls.

webrtc/pc/test/mock_webrtcsession.h

 /*
  *  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.
  */
 
@@ skipping 32 matching lines @@
                     nullptr,
                     /*redetermine_role_on_ice_restart=*/true,
                     rtc::CryptoOptions())),
             std::unique_ptr<cricket::SctpTransportInternalFactory>()) {}
   MOCK_METHOD0(voice_channel, cricket::VoiceChannel*());
   MOCK_METHOD0(video_channel, cricket::VideoChannel*());
   // Libjingle uses "local" for a outgoing track, and "remote" for a incoming
   // track.
   MOCK_METHOD2(GetLocalTrackIdBySsrc, bool(uint32_t, std::string*));
   MOCK_METHOD2(GetRemoteTrackIdBySsrc, bool(uint32_t, std::string*));
+  MOCK_METHOD0(GetCallStats, Call::Stats());
   MOCK_METHOD1(GetStats,
                std::unique_ptr<SessionStats>(const ChannelNamePairs&));
   MOCK_METHOD2(GetLocalCertificate,
                bool(const std::string& transport_name,
                     rtc::scoped_refptr<rtc::RTCCertificate>* certificate));
 
   // Workaround for gmock's inability to cope with move-only return values.
   std::unique_ptr<rtc::SSLCertificate> GetRemoteSSLCertificate(
       const std::string& transport_name) /* override */ {
     return std::unique_ptr<rtc::SSLCertificate>(
         GetRemoteSSLCertificate_ReturnsRawPointer(transport_name));
   }
   MOCK_METHOD1(GetRemoteSSLCertificate_ReturnsRawPointer,
                rtc::SSLCertificate*(const std::string& transport_name));
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_PC_TEST_MOCK_WEBRTCSESSION_H_