Log window trace data per frame in continuous mode

When using non-continuous mode the WM Service logs each transaction
applied. This is incur in performance loss.

For continuous mode we need a more efficient mechanism to log the data,
thus we log only 1x per frame and only if a transaction has been
applied.

Test: Flash a device. Enable the continuous mode for tracing using
`adb shell cmd window tracing continuous true` and start the trace with
`adb shell cmd window tracing start`. Use the device. To stop the trace
and log the data to disk use `adb shell cmd window tracing stop`. Open
the trace in Winscope and check if all `entry` elements have the
following property: `where: onFrame`

Change-Id: I1034d9e1b7b8a105d4e16a1aeb4b7341fff5f157