Change NNAPI time from steady_clock to boot_clock -- hal

Previously, the NNAPI used std::chrono::steady_clock to represent and
measure timings. However, steady_clock does not count while the system
is suspended. Instead, boot_clock is monotonic like steady_clock but
does include the time when the system is suspended.

This change also indicates that services may convert from
std::chrono::steady_clock::time_point to
android::base::boot_clock::time_point in the HIDL 1.3 NN HAL.

Bug: 183118340
Test: mma
Test: VtsHalNeuralnetworksV1_3TargetTest
Test: VtsHalNeuralnetworksTargetTest
Test: presubmit
Change-Id: I5a7d039a31d9ce98602a301387ec99635f279f42
diff --git a/neuralnetworks/1.3/IDevice.hal b/neuralnetworks/1.3/IDevice.hal
index e0b04a8..de889e4 100644
--- a/neuralnetworks/1.3/IDevice.hal
+++ b/neuralnetworks/1.3/IDevice.hal
@@ -131,6 +131,14 @@
      * ErrorStatus::MISSED_DEADLINE_TRANSIENT} or {@link
      * ErrorStatus::MISSED_DEADLINE_PERSISTENT} may be returned. The error due
      * to an abort must be sent the same way as other errors, described above.
+     * The deadline is represented as nanoseconds since the epoch of the steady
+     * clock (as if from std::chrono::steady_clock::time_point), but the service
+     * may convert it to the nanoseconds since boot time (as if from
+     * clock_gettime(CLOCK_BOOTTIME, &ts) or
+     * android::base::boot_clock::time_point) to account for time when the
+     * system is suspended. This conversion can by done by finding the timeout
+     * duration remaining compared to the steady_clock and adding it to the
+     * current boot_clock time.
      *
      * Optionally, the driver may save the prepared model to cache during the
      * asynchronous preparation. Any error that occurs when saving to cache must
@@ -249,7 +257,15 @@
      * ErrorStatus::MISSED_DEADLINE_TRANSIENT}
      * or {@link ErrorStatus::MISSED_DEADLINE_PERSISTENT} may be returned. The
      * error due to an abort must be sent the same way as other errors,
-     * described above.
+     * described above. The deadline is represented as nanoseconds since the
+     * epoch of the steady clock (as if from
+     * std::chrono::steady_clock::time_point), but the service may convert it to
+     * the nanoseconds since boot time (as if from
+     * clock_gettime(CLOCK_BOOTTIME, &ts) or
+     * android::base::boot_clock::time_point) to account for time when the
+     * system is suspended. This conversion can by done by finding the timeout
+     * duration remaining compared to the steady_clock and adding it to the
+     * current boot_clock time.
      *
      * The only information that may be unknown to the model at this stage is
      * the shape of the tensors, which may only be known at execution time. As