mac: Fix tab dragging visual bug in Yosemite. (reland 2)

mac: Fix tab dragging visual bug in Yosemite. (reland 2)
-----------------Reland 2 Description------------------
Turned on layers for the test for fullscreen windows.

-----------------Reland 1 Description------------------
Reland 1 link: https://codereview.chromium.org/393933003/
Core animation was turned on in M35. The fullscreen window was not layer
backed, but should have been. This original CL exposed this bug.

-----------------Original Description------------------
Original CL link: https://codereview.chromium.org/379293003/

In OSX 10.10+, all views must be added to the NSWindow's contentView. Some
views (like the tab strip and the profile icon) are placed on top of the title
bar and require special treatment. All other views are added as subviews of
'chromeContentView' in TabWindowController. This allows tab dragging and
fullscreen logic to easily move the views that don't need special treatment.

This CL also removes the instances where a VersionIndependentWindow's
contentView gets replaced by setContentView:. Instead, the 'chromeContentView'
gets passed around as a subview. This allows VersionIndependentWindow to remove
another of its internal hacks.

BUG=392239
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283650

[erikchen, 2014-07-17 00:10:25]

shess: Please review.

[Scott Hess - ex-Googler, 2014-07-17 00:13:01]

Change LGTM, but ... is there something causing this to miss trybot coverage or
something?

[erikchen, 2014-07-17 00:17:45]

yeah, the exception being raised in an OSX 10.6 bug, and the trybots don't run
on 10.6.

[erikchen, 2014-07-17 00:20:29]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2014-07-17 00:23:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/erikchen@chromium.org/399803002/20001

[commit-bot: I haz the power, 2014-07-17 05:10:12]

Change committed as 283650

[erikchen, 2014-07-29 01:17:32]

A revert of this CL has been created in
https://codereview.chromium.org/423013005/ by erikchen@chromium.org.

The reason for reverting is: NSInvalidArgumentException reason Unlocking Focus
on wrong view (<NSView: 0x#>), expected <FastResizeView: 0x#>	

https://code.google.com/p/chromium/issues/detail?id=397089.