Interface to control the visual event tracer feature. The result
is a log of various events that are monitored by a custom code
instrumentation around the mozilla code base.
Start the logging now. No affect if already started.
Current backlog is deleted by this call otherwise.
| minBacklogSeconds | Manimum time to keep the backlog. Entries of the log are discarded when their age is more then value of this argument. |
Stop the logging now. Backlog is kept in memory.
Obtain the log. This can be called whenever you want.
| Result is an object that keeps snaphot of the log from time this method has been called. You can then access the log using the object. Calling stop() on the tracer doesn't delete this log. |