Roll WebRTC 17902:17923 (13 commits)

Changes: https://chromium.googlesource.com/external/webrtc/trunk/webrtc.git/+log/f66bef3..5515dcd

$ git log f66bef3..5515dcd --date=short --no-merges --format=%ad %ae %s
2017-04-28 denicija@webrtc.org iOS/MacOS:Refactor metal rendering by extracting common implementation in separate super class.
2017-04-28 henrik.lundin@webrtc.org Add NetEqInput::PacketData::ToString method
2017-04-28 henrik.lundin@webrtc.org NetEq tests: BUILD target reorg
2017-04-27 zijiehe@chromium.org Forward capturer_id between DesktopFrame and its implementations
2017-04-27 glaznev@webrtc.org Reland of Support adding and removing MediaRecorder to camera 2 session. (patchset #1 id:1 of https://codereview.webrtc.org/2844233002/ )
2017-04-27 mbonadei@webrtc.org Hiding problematic targets from chromium
2017-04-27 ossu@webrtc.org Have AudioSendStream register CNG payload types with the RtpRtcpModule.
2017-04-27 brandtr@webrtc.org Add warning about timestamp non-monotonicity in the frame buffer.
2017-04-27 hewwatt@gmail.com This CL adds RTCMTLVideoView.h and RTCCameraVideoCapturer.h to WebRTC.h in order to fix a build issue that comes up when using WebRTC.framework from swift code.
2017-04-27 kwiberg@webrtc.org Run some peer connection end-to-end tests with an empty audio decoder factory
2017-04-27 magjed@webrtc.org Revert of Support adding and removing MediaRecorder to camera 2 session. (patchset #5 id:80001 of https://codereview.webrtc.org/2833773003/ )
2017-04-27 ossu@webrtc.org Injectable audio encoders: WebRtcVoiceEngine and company
2017-04-27 ossu@webrtc.org Normalize codec names to those used by AcmCodecDatabase.

TBR=
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_archive_rel_ng;master.tryserver.chromium.mac:mac_chromium_archive_rel_ng
BUG=

Review-Url: https://codereview.chromium.org/2849793002
Cr-Commit-Position: refs/heads/master@{#467957}

DEPS

@@ -235,7 +235,7 @@ deps = {
     Var('chromium_git') + '/native_client/src/third_party/scons-2.0.1.git' + '@' + '1c1550e17fc26355d08627fbdec13d8291227067',
 
   'src/third_party/webrtc':
-    Var('chromium_git') + '/external/webrtc/trunk/webrtc.git' + '@' + 'f66bef3fb3abbba3378d22f714b0d1ffaf159677', # commit position 17902
+    Var('chromium_git') + '/external/webrtc/trunk/webrtc.git' + '@' + '5515dcd0567c4df4f3cdd9487f4f1556e558dfc3', # commit position 17923
 
   'src/third_party/openmax_dl':
     Var('chromium_git') + '/external/webrtc/deps/third_party/openmax.git' + '@' +  Var('openmax_dl_revision'),