Tighten up Binder.clearCallingIdentity() usage.

This is a third CL in a chain that adjusts existing malformed code
to follow AndroidFrameworkBinderIdentity best-practices.

Specifically, if a thread clears an identity they need to restore it
to avoid obscure security vulnerabilities.  In addition, the relevant
"try" block must start immediately after the identity is cleared to
ensure that its restored if/when any exceptions are thrown.

Bug: 155703208
Test: make
Exempt-From-Owner-Approval: trivial refactoring
Change-Id: I74cb958b68d55a647547aae21baff6ddc364859b