[win] Add utility function to find out if chrome is installed.

The app launcher can be used with or without chrome installed. This function
lets the app launcher find out if chrome is installed.

BUG=159733


Review URL: https://chromiumcodereview.appspot.com/12094053

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@180329 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed