Support extension search engines.

BUG=267510
TBR=mpcomplete@chromium.org

Review URL: https://codereview.chromium.org/26654013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231316 0039d316-1c4b-4281-b951-d872f2087c98
Added collecting of data to be fed to the JTL interpreter.

BUG=298036

Review URL: https://codereview.chromium.org/27030002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231317 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231317
Using the new WebMediaStreamTrack::ExtraData to simplify the code
Always store the native MediaStreamTrackInterface in the ExtraData field.

This patch doesn't change the current behavior.

BUG=294145

Review URL: https://codereview.chromium.org/31033003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231318 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231318