Clean up native AlarmManagerService tabs/spaces and unused parameter warnings

Change-Id: I64da1437dd0ed30957b43450c72b9d3797112a2e
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Add timerfd backend to AlarmManagerService

On devices without /dev/alarm, use a new backend based on timerfd.
timerfd has near-equivalent syscalls for the /dev/alarm ioctls we care
about, with two key differences:

1) /dev/alarm uses one fd for all clocks, while timerfd needs one fd per
clock type.

AlarmManagerService addresses this by replacing the fd (int) with an
opaque pointer (long) to the backend-specific state.

2) When the RTC changes, the /dev/alarm WAIT ioctl always returns, while
timerfd cancels (and signals events) only on specially-flagged RTC
timerfds.

The timerfd backend masks this by creating an extraneous RTC timerfd,
specifically so there's always something to signal on RTC changes.

Change-Id: I5aef867748298610347f6e1479dd8bf569495832
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Add /dev/rtc backend to SystemClock

On devices without /dev/alarm, use the settimeofday() syscall and the
standard RTC_SET_TIME ioctl (which are collectively equivalent to the
ANDROID_ALARM_SET_RTC ioctl).

Change-Id: I3c1d741099e253186e43c9369b62603b214b9c9a
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Fix to NullPointerException on move back in ActivityStack.

In ActivityTask.moveTaskToBackLocked NullPointerException may occur
when moving back with only current Activity in stack. This due to a
condition that may trigger despite a TaskRecord being null and then
attempt accessing the TaskRecord.mOnTopOfHome variable.

TaskRecord task may be set to null when no resumed activity remain.

Resolved by assuring that flag mOnTopOfHome is instead set to false
for current TaskRecord in case where there are no remaining activities
above home.

The above bug has already been corrected in the following commit,
ada62fca51d314cefe2c5da4e007df5b9abf320d, but it does not set the
cottect value to mTopOfHome for the current taks, see below.

Variable mOnTopOfHome will not be set to false in situations where
stack is of size 1 or less and task is null, perhaps from already
having finished current activity.

To avoid current TaskRecord maintaining value mOnTopOfHome to true
after launching Home this variable is set to false.

Impact should not be major due to correction earlier that makes sure
that there is always a TaskRecord.mOnTopOfHome set to true above Home
activity but if not correctly set for current task still gives a
possibility of bad behavior.

Change-Id: Ie86ad99c188aaa05b0de9d58eaa16c42b6fc4341
Merge "Fix to NullPointerException on move back in ActivityStack."
Merge "Clean up native AlarmManagerService tabs/spaces and unused parameter warnings"
Merge "Add timerfd backend to AlarmManagerService"
Merge "Add /dev/rtc backend to SystemClock"