Update Android about:flags

* Deletes command line flags used by "Add to homescreen" because it
  is now enabled by default.
* Adds a command line flag to disable app banners.

NOTRY=true
BUG=332281

Review URL: https://codereview.chromium.org/139993011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248733 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248733