There were window leak in the settings application.
These leak happens when an AlertDialog displays, rotate the phone,
then it would cause window leak.
Change-Id: I914897bf657933efea72eeea66076dc288098420
Handle the back key.
Finish the activity if dialog is cancelled.
Show an error and finish the activity if URL couldn't be found due to
connectivity problem and not just when Telephony is not available.
The Safety information link is stored in a system property, ro.url.safetylegal
If the phone has data connection, select "Safety information" menu will open the
Safety information link. If there is no data connection for the phone, a message will
pop up which ask user to open Safety information link from PC.
Change-Id: Ia46e2e868ebcda93138cb9f00c978d8ac827022a
