People: Use PhoneCapabilityTester.isUsingTwoPanes ...

instead of mContentPaneDisplayed.

I'm trying to clean up the fragment stuff.  Using isUsingTwoPanes()
seems cleaner than using the old flag, which gets updated in onAttachFragment.

Change-Id: Id894d5679d4d3928794d5f67d87967a7ae849cf5
1 file changed