Acquire the current time.
#include <zircon/syscalls.h> zx_time_t zx_clock_get(zx_clock_t clock_id);
zx_clock_get() returns the current time of clock_id, or 0 if clock_id is invalid.
ZX_CLOCK_MONOTONIC number of nanoseconds since the system was powered on.
ZX_CLOCK_UTC number of wall clock nanoseconds since the Unix epoch (midnight on January 1 1970) in UTC
ZX_CLOCK_THREAD number of nanoseconds the current thread has been running for.
TODO(ZX-2399)
On success, zx_clock_get() returns the current time according to the given clock ID.
On error, zx_clock_get() returns 0.