Send incoming call directly to CallReceiver

Remove CallActivity from the flow that happens when an incoming call
is received. This fixes the problem where the foreground activity is
paused when an incoming call is received. This also has the benefit
of eliminating any potential latency the CallActivity could have
introduced.

Bug: 17703900

Change-Id: Ibed8aa3fb8d1a88fec27435330b26aa1ed4fc3aa
4 files changed