Collapse the API surface on WebInputEvent via accessor functions.

blimp/client/core/input/blimp_input_handler_wrapper.cc

Index: blimp/client/core/input/blimp_input_handler_wrapper.cc
diff --git a/blimp/client/core/input/blimp_input_handler_wrapper.cc b/blimp/client/core/input/blimp_input_handler_wrapper.cc
index e2b893109bebc34c054ca5dac39213e35480edfb..3bc549c87c035a13be9f3773ba3ccb8b3f515283 100644
--- a/blimp/client/core/input/blimp_input_handler_wrapper.cc
+++ b/blimp/client/core/input/blimp_input_handler_wrapper.cc
@@ -101,7 +101,7 @@ void BlimpInputHandlerWrapper::DispatchNonBlockingEventToMainThread(
     blink::WebScopedInputEvent event,
     const ui::LatencyInfo& latency_info) {
   DCHECK(compositor_thread_checker_.CalledOnValidThread());
-  DCHECK_EQ(event->type, blink::WebInputEvent::MouseWheel);
+  DCHECK_EQ(event->type(), blink::WebInputEvent::MouseWheel);
 
   NOTIMPLEMENTED()
       << "Dispatching Non Blocking Events to the engine is not supported";