"Prepatch" for issue 13713 (resize tabstrip upon resizing window on...

Superseded by CL 159346:
http://codereview.chromium.org/159346

"Prepatch" for issue 13713 (resize tabstrip upon resizing window on
Mac). It's a "prepatch" since part of the code is obviously rubbish (see
below); otherwise it seems to work fine. This just entails getting the
TabStripController's TabStripView to post notifications, and the
TabStripControlller to receive them (and when it does, it re-lays-out
the tabs).

The rubbish: We need an unanimated version of -layoutTabs (in
TabStripController). I've actually split the current one into three: two
public interfaces, -layoutTabs and -layoutTabsFast, and an internal one,
-layoutTabsInternal. -layoutTabsInternal is currently the world's
quickest and ugliest cut-and-paste job (from the old -layoutTabs), and
is just there to show that things work, before someone produces a proper
version. (For the unanimated version, I just excised parts which
mentioned animation, and didn't bother to understand the code. I didn't
want to rewrite the layout code, since I think it's currently being
worked on by pinkerton.)

Patch Set 3: Haven't cleared any rubbish yet -- just tracking the
current version. Hopefully this patch set will hold up better to merges.

BUG=13713
TEST=make lots of tabs and resize window; watch tab strip adapt