Currently when dispatching events to the renderer we convert from ui::Event to mojom::Event. Then we convert from mojom::Event to blink::WebInputEvent.

With mus::InputEventHandler now using ui::Event this extra conversion is unnecessary. We should clean this up when we setup the direct posting of events from mus to the chrome renderer.

Eg: CompositorMusConnection::OnWindowInputEvent calls:

 std::unique_ptr<blink::WebInputEvent> web_event(
      mus::mojom::Event::From(event)
          .To<std::unique_ptr<blink::WebInputEvent>>());

Which first converts using InputEventTypeConverters:
mus::mojom::EventPtr TypeConverter<mus::mojom::EventPtr, ui::Event>::Convert(
    const ui::Event& input)

Then uses BlinkInputEventTypeConverters:
scoped_ptr<blink::WebInputEvent>
TypeConverter<scoped_ptr<blink::WebInputEvent>, mus::mojom::EventPtr>::Convert