MD Settings: Lazy load the contents of the "advanced" settings.

chrome/browser/resources/settings/settings_page/main_page_behavior.js

Index: chrome/browser/resources/settings/settings_page/main_page_behavior.js
diff --git a/chrome/browser/resources/settings/settings_page/main_page_behavior.js b/chrome/browser/resources/settings/settings_page/main_page_behavior.js
index 8fdf5f7e6e61f2e949d67e6f8acaa3df9fce936d..40ac65815a1bf3b43ae3f117521d966e04b948db 100644
--- a/chrome/browser/resources/settings/settings_page/main_page_behavior.js
+++ b/chrome/browser/resources/settings/settings_page/main_page_behavior.js
@@ -116,6 +116,11 @@ var MainPageBehaviorImpl = {
         promise = this.expandSection_(currentSection);
       else if (scrollToSection)
         currentSection.scrollIntoView();
+    } else if (settings.Route.ADVANCED.contains(currentRoute) &&
+        // Need to exclude routes that correspond to 'non-sectioned' children of
+        // ADVANCED, otherwise tryTransitionToSection_ will recurse endlessly.
+        !settings.isNavigableDialog(currentRoute)) {
+      promise = this.$$('#advancedPageTemplate').get();
     }
 
     // When this animation ends, another may be necessary. Call this function