Make hosted app icons work on win-aura

Code should only return false on ash, which isn't the case on win-aura.
This was causing hosted apps that were run as window to not get their
window icons set.

TEST=Right click the Drive app in the new tab page and run it as a window. The new window that appears should have the Drive icon as its taskbar icon and favicon.
BUG=305512

Review URL: https://codereview.chromium.org/26613003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228136 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228136
[SyncFS] Thread restriction fix on a error case of DriveMetadataStore

TEST=n/a
NOTRY=true

Review URL: https://codereview.chromium.org/26223003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228137 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228137