am b68162a9: cherrypick Change-Id: I60c74919ab3df359f47e5052bcc1469318a5b821 add notice about large screen devices and the "mobile" string in user agent

* commit 'b68162a9d6212598a529d63079db15bea6da654c':
  cherrypick Change-Id: I60c74919ab3df359f47e5052bcc1469318a5b821 add notice about large screen devices and the "mobile" string in user agent