Show connection type in web-app.

This is mostly boilerplate to get the OnSessionRouteChange notification up to the web-app. The web-app then includes it in the stats panel. In the common case where all channels have the same type, it displays it as "connection: <type>"; if the types differ they are displayed individually.

BUG=134528

Review URL: https://codereview.chromium.org/126123002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243947 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243947