Remove InsecureContentInfobarDelegate, which has been broken for a while

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 866943a399e41244d27c7bdf378ad140c968c069..450ba0bbb85ec2ef2109cd217ea2f1e939121c2d 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1003,8 +1003,6 @@ void RenderView::ApplyWebPreferences(const WebPreferences& prefs,
   // ChromeClient::tabsToLinks which is part of the glue code.
   web_view->setTabsToLinks(prefs.tabs_to_links);
 
-  settings->setAllowDisplayOfInsecureContent(
-      prefs.allow_displaying_insecure_content);
   settings->setAllowRunningOfInsecureContent(
       prefs.allow_running_insecure_content);
   settings->setDisableReadingFromCanvas(prefs.disable_reading_from_canvas);