Remove unnecessary virtual.

This is leftover from https://codereview.chromium.org/2715513004. This
will remove HttpAuthController's vtable and hopefully decrease code
size.

Change-Id: I61dbc388f006234a64cb0a87d6475c12ba6b724e
Reviewed-on: https://chromium-review.googlesource.com/1187731Reviewed-by: Asanka Herath <asanka@chromium.org>
Commit-Queue: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585879}

net/http/http_auth_controller.h

@@ -103,7 +103,7 @@ class NET_EXPORT_PRIVATE HttpAuthController
   // So that we can mock this object.
   friend class base::RefCounted<HttpAuthController>;
 
-  virtual ~HttpAuthController();
+  ~HttpAuthController();
 
   // Searches the auth cache for an entry that encompasses the request's path.
   // If such an entry is found, updates |identity_| and |handler_| with the