base

Don't call public non-final getResources() from getAssets()

Refactors to getResourcesInternal() and calls that from both methods.
Adds documentation on Context.getResources() and getAssets() that the
instances returned should be consistent with each other.

Bug: 26228895
Change-Id: I41b09f1e9a3a0315bcdf1c08a7b431a9a697bb6f