TrackMediaInfoMap added.

This maps, in both directions, [Audio/Video]TrackInterface with
[Voice/Video][Sender/Receiver]Info.

This mapping is necessary for RTCStatsCollector to know the relationship
between RTCMediaStreamTrackStats and RTC[In/Out]boundRTPStreamStats, and
to be able to collect several RTCMediaStreamTrackStats stats.

BUG=webrtc:6757, chromium:659137, chromium:657854, chromium:627816

Review-Url: https://codereview.webrtc.org/2611983002
Cr-Commit-Position: refs/heads/master@{#16090}
diff --git a/webrtc/api/test/mock_rtpreceiver.h b/webrtc/api/test/mock_rtpreceiver.h
new file mode 100644
index 0000000..25f5c28
--- /dev/null
+++ b/webrtc/api/test/mock_rtpreceiver.h
@@ -0,0 +1,34 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
+#define WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
+
+#include <string>
+
+#include "webrtc/api/rtpreceiverinterface.h"
+#include "webrtc/test/gmock.h"
+
+namespace webrtc {
+
+class MockRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface> {
+ public:
+  MOCK_METHOD1(SetTrack, void(MediaStreamTrackInterface*));
+  MOCK_CONST_METHOD0(track, rtc::scoped_refptr<MediaStreamTrackInterface>());
+  MOCK_CONST_METHOD0(media_type, cricket::MediaType());
+  MOCK_CONST_METHOD0(id, std::string());
+  MOCK_CONST_METHOD0(GetParameters, RtpParameters());
+  MOCK_METHOD1(SetParameters, bool(const RtpParameters&));
+  MOCK_METHOD1(SetObserver, void(RtpReceiverObserverInterface*));
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_