In #1024, it was shown that when using the Crosswalk Webview, the user agent parsing in Werkzeug would categorize Crosswalk as ChromeOS rather than Android although it was running on Android.

This occurred as we rely on matching cros anywhere in the UA string to determine if a UA is from ChromeOS. Upon reviewing ChromeOS UA strings, it became clear that CrOS is always surrounded by a space on either side. As such, this change makes us check for cros instead of cros and adds test coverage for this case.

It should be noted that on #1024, @alexpantyukhin proposes ensuring we check all strings as separate words (e.g. expecting a space on either side or the beginning or end of line). This may be reasonable but I'm unclear of how it might affect parsing other UA strings that aren't covered in the test cases.