kiosk: Enable Ctrl +/-/0 zoom content accelerators for app windows.

We do not enable these for app windows in general, because the user
can already adjust the zoom using the page view settings. However, 
this is not possible in ChromeOS Kiosk mode. This patch provides a way
to zoom app windows in ChromeOS Kiosk mode.

It's a minimum subset of mlamouri's
  https://codereview.chromium.org/97003002/ to fix the bug.

BUG=341235

Review URL: https://codereview.chromium.org/155743002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249666 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249666
Skip root dir when iterating over path in reparse points search.

It turns out that ::GetFileAttributes(...) Windows API for paths in form of "<drive>:" returns attribute of binary file work dir instead of "<drive>:\"
dir.

BUG=340625

Review URL: https://codereview.chromium.org/150093006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249667 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249667
Suppress NOTREACHED logs from file manager.

It seems window_manager can return a stub object rather than NULL
when the feature is disabled.

BUG=none

Review URL: https://codereview.chromium.org/153753004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249668 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249668