Adding chrome://sessions webui for prototyping tab sync NTP stuff.

This adds the necessary plumbing for chrome://sessions webui page which shows a hierarchy of sessions and their windows and tabs as well as a "magic" list of suggested tabs. The magic list is currently just the last 10 tabs by timestamp for now - but can later be changed to prototype other heuristics.

BUG=none
TEST=manual

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=88334
Review URL: http://codereview.chromium.org/6969016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@88364 0039d316-1c4b-4281-b951-d872f2087c98
11 files changed