Use milliseconds for timing.

bramble-api/src/main/java/org/briarproject/bramble/api/system/Clock.java

@@ -11,11 +11,6 @@ public interface Clock {
 	 */
 	long currentTimeMillis();
 
-	/**
-	 * @see System#nanoTime()
-	 */
-	long nanoTime();
-
 	/**
 	 * @see Thread#sleep(long)
 	 */

bramble-api/src/test/java/org/briarproject/bramble/test/ArrayClock.java

@@ -16,11 +16,6 @@ public class ArrayClock implements Clock {
 		return times[index++];
 	}
 
-	@Override
-	public long nanoTime() {
-		return times[index++] * 1_000_000;
-	}
-
 	@Override
 	public void sleep(long milliseconds) throws InterruptedException {
 		Thread.sleep(milliseconds);

bramble-api/src/test/java/org/briarproject/bramble/test/SettableClock.java

@@ -17,11 +17,6 @@ public class SettableClock implements Clock {
 		return time.get();
 	}
 
-	@Override
-	public long nanoTime() {
-		return time.get() * 1_000_000;
-	}
-
 	@Override
 	public void sleep(long milliseconds) throws InterruptedException {
 		Thread.sleep(milliseconds);