- Now we declare all fragments in the layouts.
- Added clearContent() to MessageList/MessageView to keep them calm when not
used. (e.g. MessageView.clearContent() will be called when closing message
view and going back to the mailbox list+message list screen.)
- Some of the processes have moved from onStop to onPause.
- Now that we don't use the fragment transaction, the "restored fragments"
has been removed, and the separation between selectXxx() methods and
updateXxx() methods are gone.
Bug 3045555
Bug 3041502
Change-Id: I958897a8a38bccea1dfed7cfcd900e6dd52d2eed
61eec98d39