chrome://settings - Provide method for pages to prevent themselves being shown.

chrome/browser/resources/options/alert_overlay.js

Index: chrome/browser/resources/options/alert_overlay.js
diff --git a/chrome/browser/resources/options/alert_overlay.js b/chrome/browser/resources/options/alert_overlay.js
index e8ecced70c7d5397956ccc01fdceea85b7b6b777..eb1fb8e80aeb09095beeeb413a2b975bfd78d037 100644
--- a/chrome/browser/resources/options/alert_overlay.js
+++ b/chrome/browser/resources/options/alert_overlay.js
@@ -21,6 +21,13 @@ cr.define('options', function() {
     __proto__: OptionsPage.prototype,
 
     /**
+     * Whether the page can be shown. Used to make sure the page is only
+     * shown via AlertOverlay.Show(), and not via the address bar.
+     * @private
+     */
+    canShow_: false,
+
+    /**
      * Initialize the page.
      */
     initializePage: function() {
@@ -59,7 +66,19 @@ cr.define('options', function() {
       if (this.cancelCallback != undefined) {
         this.cancelCallback.call();
       }
-    }
+    },
+
+    /**
+     * The page is getting hidden. Don't let it be shown again.
+     */
+    willHidePage: function() {
+      canShow_ = false;

[Vitaly Pavlenko, 2014/10/01 23:29:53]

This should be 

this.canShow_ = false;

right?

[Evan Stade, 2014/10/13 16:21:55]

yes

+    },
+
+    /** @inheritDoc */
+    canShowPage: function() {
+      return this.canShow_;
+    },
   };
 
   /**
@@ -108,9 +127,13 @@ cr.define('options', function() {
       $('alertOverlayCancel').style.display = 'none';
     }
 
-    AlertOverlay.getInstance().okCallback = okCallback;
-    AlertOverlay.getInstance().cancelCallback = cancelCallback;
+    var alertOverlay = AlertOverlay.getInstance();
+    alertOverlay.okCallback = okCallback;
+    alertOverlay.cancelCallback = cancelCallback;
+    alertOverlay.canShow_ = true;
 
+    // Intentionally don't show the URL in the location bar as we don't want
+    // people trying to navigate here by hand.
     OptionsPage.showPageByName('alertOverlay', false);
   }