Keeps a dummy SQLite in-memory DB connection.

In order to maintain an SQLite in-memory DB state over multiple
connections, we need to create one first and maintain a reference to
it throughout the test. Otherwise, the DB state is lost each time the
conneciton is closed.

Change-Id: I185e12ef50611b37b1270920304ac8e960249e5a
Merge "Keeps a dummy SQLite in-memory DB connection."