Implement a class for the Profiler API in dwds

[willdrach-wk]

The Chrome DevTools protocol has a Profiler API, which adds a host of helpful methods for analyzing code. In our case in particular, we would like to make use of Profiler.takePreciseCoverage and Profiler.startPreciseCoverage to generate code coverage reports.

Overall I think this would look very similar to the Sources class but even simpler. A basic implementation of this API could be as simple as this:

class Profiler {
  bool _profilerEnabled = false;
  final RemoteDebugger _remoteDebugger;

  Profiler(this._remoteDebugger);

  Future startProfiler() async {
    if (_profilerEnabled) {
      return;
    }
    _profilerEnabled = true;
    await _remoteDebugger.sendCommand('Profiler.enable');
  }

  Future startPreciseCoverage() async {
    await startProfiler();
    return _remoteDebugger.sendCommand('Profiler.startPreciseCoverage');
  }

  Future takePreciseCoverage() async {
    await startProfiler();
    return _remoteDebugger.sendCommand('Profiler.takePreciseCoverage');
  }
}

Obviously there's a million other things you could add and use, but really this is all we'd need to help get the information we want.