AppListWinUnittest: Some hard-coded constants are now computed.

BUG=317944

Review URL: https://codereview.chromium.org/104593003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238915 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238915