Remove WebContents::Was{Hidden,Shown}() from the content public interface

chrome/browser/prerender/prerender_contents.cc

Index: chrome/browser/prerender/prerender_contents.cc
diff --git a/chrome/browser/prerender/prerender_contents.cc b/chrome/browser/prerender/prerender_contents.cc
index 7a682746b3a97baa68e643129411462bb726aeee..bb51722f76b98a8ed1497c75a7100b2a4012dd4b 100644
--- a/chrome/browser/prerender/prerender_contents.cc
+++ b/chrome/browser/prerender/prerender_contents.cc
@@ -429,8 +429,11 @@ void PrerenderContents::Observe(int type,
         // thread of the browser process.  When the RenderView receives its
         // size, is also sets itself to be visible, which would then break the
         // visibility API.
+        // TODO(tapted): That comment doesn't sound right. Probably the
+        // CreateWebContents() method should just be passing |initially_hidden|
+        // as true via WebContents::CreateParams.
         new_render_view_host->GetWidget()->WasResized();
-        prerender_contents_->WasHidden();
+        prerender_contents_->MarkBackgrounded();
       }
       break;
     }