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 3198d5d8dd9f7fe3ae5ffade9ff866ed2c43b964..2cf0a6d03aeb4391f6aa8cffa0b253ba0d9008cb 100644
--- a/chrome/browser/ssl/ssl_blocking_page.h
+++ b/chrome/browser/ssl/ssl_blocking_page.h
@@ -43,8 +43,16 @@ class SSLBlockingPage : public SecurityInterstitialPage {
   };
 
   enum SSLBlockingPageOptionsMask {
+    // Indicates whether or not the user could (assuming perfect knowledge)
+    // successfully override the error and still get the security guarantees
+    // of TLS.
     OVERRIDABLE = 1 << 0,
+    // Indicates whether or not the site the user is trying to connect to has
+    // requested strict enforcement of certificate validation (e.g. with HTTP
+    // Strict-Transport-Security).
     STRICT_ENFORCEMENT = 1 << 1,
+    // Indicates whether a user decision had been previously made but the
+    // decision has expired.
     EXPIRED_BUT_PREVIOUSLY_ALLOWED = 1 << 2
   };
 
@@ -71,6 +79,11 @@ class SSLBlockingPage : public SecurityInterstitialPage {
   static void SetExtraInfo(base::DictionaryValue* strings,
                            const std::vector<base::string16>& extra_info);
 
+  static bool IsOverridable(const int options_mask) {
+    return (options_mask & SSLBlockingPage::OVERRIDABLE) &&
+           !(options_mask & SSLBlockingPage::STRICT_ENFORCEMENT);
+  }
+
  protected:
   // InterstitialPageDelegate implementation.
   virtual void CommandReceived(const std::string& command) override;