Add a unit test for BrowserViewLayout

Add a unit test for BrowserViewLayout

This is the first of several steps.
* Decouple Browser and BrowserView initialization
* Dependency inject Browser into BrowserViewLayout
* Modify BrowserWithTestWindowTest to allow it to use a BrowserView as
  its BrowserWindow
* Add some trivial assertions

BUG=233374
TEST=added unit_tests BrowserViewLayout.*

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=195301

[James Cook, 2013-04-19 03:07:38]

Ben, PTAL. I'd like to get some early feedback on my approach here.

I made some changes to BrowserViewLayout recently to support Chrome OS
immersive-mode fullscreen when instant-extended is enabled. There were no
existing tests for how instant-extended changes the BrowserView layout, and it
does some tricky stuff.

I ended up writing tests for my code in a BrowserTest, as it was the only way to
get everything instantiated with instant-extended running.  BrowserTests feel
like overkill for simple layout assertions, though, so I'm trying to get these
classes into a unit test harness so I can test BrowserViewLayout::Layout()
without all the other complexity.

[Ben Goodger (Google), 2013-04-19 16:19:43]

lgtm

[commit-bot: I haz the power, 2013-04-19 18:39:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jamescook@chromium.org/14348011/1

[commit-bot: I haz the power, 2013-04-19 20:08:00]

Retried try job too often on win_rel for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[James Cook, 2013-04-19 22:00:08]

Committed patchset #1 manually as r195301 (presubmit successful).