Collapse the API surface on WebInputEvent via accessor functions.

blimp/engine/session/tab.cc

Index: blimp/engine/session/tab.cc
diff --git a/blimp/engine/session/tab.cc b/blimp/engine/session/tab.cc
index d500c722b620004f69e41d7b9e5f5a57fe4e9448..4373994fed2db92ab5c093004069ceeb539b9818 100644
--- a/blimp/engine/session/tab.cc
+++ b/blimp/engine/session/tab.cc
@@ -167,7 +167,7 @@ void Tab::SendPageLoadStatusUpdate(PageLoadStatus load_status) {
 
 void Tab::OnWebGestureEvent(content::RenderWidgetHost* render_widget_host,
                             std::unique_ptr<blink::WebGestureEvent> event) {
-  TRACE_EVENT1("blimp", "Tab::OnWebGestureEvent", "type", event->type);
+  TRACE_EVENT1("blimp", "Tab::OnWebGestureEvent", "type", event->type());
   render_widget_host->ForwardGestureEvent(*event);
 }