MTP Streaming: Optimize block reading

Previously, due to some unoptimal code, we were doing two mtp stats per block.
This cuts it down to one mtp stat per block. Still not quite there, but working on it...

BUG=110119
TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/180783005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253980 0039d316-1c4b-4281-b951-d872f2087c98
Add DebugVisualizers

BUG=293764
R=rpaquay@chromium.org

Review URL: https://codereview.chromium.org/176893005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253981 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253981
Add a command line flag to include loopback interface in network list.

On testing devices, it's not guaranteed to have at least one network
interface available. Some WebRTC content_browsertests need one network
interface to establish a call.

A command line flag(--allow-loopback-in-peer-connection) is added to ensure
loopback interface is available for those tests.

BUG=346721
R=creis@chromium.org, sergeyu@chromium.org

Review URL: https://codereview.chromium.org/181503012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253982 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253982