Adds getLayoutInflater() to return a cached value.

Bug 37156970

Many applications need to get the LayoutInflater used for
fragment View inflation. onGetLayoutInflater() can be heavy
weight, so a version that caches that last value is added.

Test: ran fragment tests
Change-Id: I11d719d7416a5bb3b65f37a78e6ed96a69c32332
4 files changed