Provide alternative SendGazeReportXX() method without timestamp

[jatinsha]

SendGazeReportUm(long X, long Y, unsigned long long timestamp);
SendGazeReportPixel(long X, long Y, unsigned long long timestamp);

The current SendGazeReportXX methods expect timestamp to be supplied by the user. In certain scenarios, the user may not have timestamps and should be able to use the API where the API itself calculates the timestamps internally.

[jatinsha]

I am assuming that the timestamp is in milliseconds but it would be good to have a short description (or a more descriptive name) that tells whether it is relative or from epoch. E.g. timestamp_ms_from_epoch, timestamp_ms_relative etc.

[joncamp]

Good point, clarity would definitely help in this case. in reality I believe under the covers it is mostly ignored as long as it is positive and increasing, but we should do the right thing.

[joncamp]

Sending 0 will automatically generate a timestamp.