Make mouse wheel events trigger WebContentsObserver::DidGetUserInteraction.

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index 37f28b1191abe06936caf47801ade9828344e210..8ccae7cba2c12f21b44353da3774fbdcc924f7a3 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -319,8 +319,9 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
   virtual void DidGetUserGesture() {}
 
   // Called when there has been direct user interaction with the WebContents.
-  // Direct user input includes 1) any mouse down event; 2) any raw key down
-  // event; and 3) any gesture tap event (including taps and scrolls).
+  // Direct user input includes 1) any mouse down event; 2) the start of a mouse
+  // wheel scroll; 3) any raw key down event; and 3) any gesture tap event

[tdresser, 2015/11/02 15:02:10]

It might be worth putting each item on it's own line in this list.

Also, replace "3) any gesture" -> "4) any gesture".

[dominickn, 2015/11/02 23:41:14]

Done.

+  // (including taps and scrolls).
   virtual void DidGetUserInteraction(const blink::WebInputEvent::Type type) {}
 
   // This method is invoked when a RenderViewHost of this WebContents was