Give the browser window's content view a CALayers

This is necessary to ensure correct ordering of the CALayers
of the child NSViews of the window's content view. Most of
the time the NSViews appeared in the correct order, but
not all of the time (especially on 10.6). This fixes that issue.

Remove code to dynamically do this when entering and leaving
presentation mode.

Update the FastResizeView to host a white CALayer instead of
trying to call drawRect, and make the NSView opaque.

This caused a performance drop last time it was tried, but other
performance fixes, and the FastResizeView fix might make it so
that this does not have an appreciable performance impact.

BUG=348490
NOTRY=True

Review URL: https://codereview.chromium.org/184433005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255150 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255150