content: convert SSL notifications to observer usage (take 2)

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 62be7d10c4fea0a491e5b7eaa3bb20d80c39d5c0..f58f57d4a8eeacaefa0f5c22fd4130fff25223a0 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -249,6 +249,9 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
   virtual void DidShowFullscreenWidget(int routing_id) {}
   virtual void DidDestroyFullscreenWidget(int routing_id) {}
 
+  // Invoked when visible SSL state (as defined by SSLStatus) changes.
+  virtual void DidChangeVisibleSSLState() {}
+
   // IPC::Listener implementation.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;