add event type enum to proto def

// Wrapper for System UI log events

message MetricsEvent {

  // Types of events

  enum Type {

    // Unknown

    TYPE_UNKNOWN = 0;

    // The view became visible to the user.

    TYPE_OPEN = 1;

    // The view became hidden.

    TYPE_CLOSE = 2;

    // The view switched to detail mode (most relevant for quick settings tiles)

    TYPE_DETAIL = 3;

    // The view or control was activated.

    TYPE_ACTION = 4;

    // The view or control was dismissed.

    TYPE_DISMISS = 5;

  }

  // Known visual elements: views or controls.

  enum View {

    // Unknown view