Merge "Fixes crash when pinning unfocused task in multiwindow"

        long ident = Binder.clearCallingIdentity();

        try {

            synchronized (this) {

                startLockTaskModeLocked(mStackSupervisor.anyTaskForIdLocked(taskId),

                        true /* isSystemCaller */);

                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId);

                // When starting lock task mode the stack must be in front and focused

                task.getStack().moveToFront("startSystemLockTaskMode");

                startLockTaskModeLocked(task, true /* isSystemCaller */);

            }

        } finally {

            Binder.restoreCallingIdentity(ident);