Add custom interstitial for captive portals.

chrome/browser/ssl/ssl_blocking_page.h

Index: chrome/browser/ssl/ssl_blocking_page.h
diff --git a/chrome/browser/ssl/ssl_blocking_page.h b/chrome/browser/ssl/ssl_blocking_page.h
index ae771be02f4a42ff1d23a021fd9683f1967e3c89..c1389723510c8173ff56e01a4eea81b7c932e6d0 100644
--- a/chrome/browser/ssl/ssl_blocking_page.h
+++ b/chrome/browser/ssl/ssl_blocking_page.h
@@ -86,13 +86,13 @@ class SSLBlockingPage : public content::InterstitialPageDelegate,
   base::Callback<void(bool)> callback_;
 
   content::WebContents* web_contents_;
-  int cert_error_;
+  const int cert_error_;
   const net::SSLInfo ssl_info_;
-  GURL request_url_;
+  const GURL request_url_;
   // Could the user successfully override the error?
-  bool overridable_;
+  const bool overridable_;
   // Has the site requested strict enforcement of certificate errors?
-  bool strict_enforcement_;
+  const bool strict_enforcement_;
   content::InterstitialPage* interstitial_page_;  // Owns us.
   // Is the hostname for an internal network?
   bool internal_;