App crashed as it was moving to foreground and message was received

Bug 7540115

In the MmsSmsProvider, wrap the code that creates a new thread in a transaction.
Creating a new thread requires multiple database operations. It's possible
for the newly created thread to be deleted part of the way through the
operation.

Change-Id: I3cbf8ba4ad3f3f30b513280ac3defc276b4a70a0