Gets the debug level stats for webrtc-internals.
This will enable displaying the BWE debug stats on chrome://webrtc-internals.
The JS is updated to special case the propagation delta value because the
value of the stat is a list and its timestamp is in the value of stat
receivedPacketGroupArrivalTime.

BUG=338380

Review URL: https://codereview.chromium.org/139473006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251795 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251795
Reenable a couple of tests which already pass in interactive_ui_tests on Linux Aura

BUG=163931
TBR=erg

Review URL: https://codereview.chromium.org/157713003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251796 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251796