cros: Trigger immersive mode with F4 maximize key

cros: Trigger immersive mode with F4 maximize key

This is a UI experiment that may be reverted for M26 depending on feedback.

* Ensure ImmersiveModeController always watches for window property changes.
* Trigger immersive mode in ChromeShellDelegate (this is only triggered by F4)
* Ensure we hide the immersive mode button when window isn't maximized (there
  are ordering issues with the window observers for show state that exit
  immersive mode vs. hide the button)

BUG=170167
TEST=added to browser_tests ImmersiveModeController.*


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=177194

[James Cook, 2013-01-16 01:00:26]

Sky, PTAL.  kuscher@ requested this change to push users into immersive mode a
bit more often.  After this change we're going to let immersive mode sit for a
week or two, then make a decision about finishing it versus keeping it out.

https://codereview.chromium.org/11969006/diff/1/chrome/browser/ui/views/frame...
File chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc (right):

https://codereview.chromium.org/11969006/diff/1/chrome/browser/ui/views/frame...
chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc:212:
immersive_button_->SetVisible(frame()->IsMaximized());
This is the core change, but I thought it was clearer to write all this as an
if() than more complex boolean expressions.

[sky, 2013-01-16 15:05:04]

LGTM

[commit-bot: I haz the power, 2013-01-16 16:55:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jamescook@chromium.org/11969006/1

[commit-bot: I haz the power, 2013-01-16 19:33:50]

Change committed as 177194