Merge third_party/libjingle/source/talk from https://chromium.googlesource.com/external/webrtc/trunk/talk.git at 7d974c11e23898cd59838c79751b96c45b09ec4b

This commit was generated by merge_from_chromium.py.

Change-Id: If28216ffbc16e927cf326c567601f482dd2bf36b