Protect use of onFindViewById for Fragment Transitions.

Bug 34163850

onFindViewById is only valid once the Fragment's View
has been created, but the child fragment manager
can be used prior to its creation. This protects
the use of onFindViewById from use by fragment
transitions.

Test: Ic72cd7dae8d7982b78258116e7910c4f07d75d50

Change-Id: I67e3b2d5f59c2e741f29211d08ab07476c78a0ca