Fix "the note of contact can't be deleted successfully"

Reproduce step:
1.login Google account
2.launch the "Contacts" app
3.Edit a new contact and click the button "ADD ANOTHER FIFLED">select "Notes" item>Edit notes to this contact
4.Check this contact info include notes
5.Click "Edit" icon and clear the edited notes info
6.click top-left icon "√"
7.Check the contact info and found the note still exist.
Analysis:
When the only entry deleted, the mAboutCard fails to refresh its entries as
the size is 0. So shouldShow() will return true based on the old data.

Change-Id: I852443f60c7ce7df10d045b1d5f7baabccb35606