Settings Router Refactor: Update subpage-back button to use history back sometimes.

chrome/browser/resources/settings/route.js

Index: chrome/browser/resources/settings/route.js
diff --git a/chrome/browser/resources/settings/route.js b/chrome/browser/resources/settings/route.js
index 096b3c13c9ecc79ea540eec75d273a1504609128..70bd0ca3e1961a726c3c11ca7222726f775b6a34 100644
--- a/chrome/browser/resources/settings/route.js
+++ b/chrome/browser/resources/settings/route.js
@@ -365,8 +365,10 @@ cr.define('settings', function() {
         url += '?' + queryString;
     }
 
+    // History serializes the state, so we don't push the actual route object.
+    var state = { previousRoutePath: currentRoute_.path };

[dpapad, 2016/08/10 22:04:03]

Can we not push the string directly instead of an object?

var previousRoutePath = currentRoute_.path;
setCurrentRoute(route, params);
window.history.pushState(previousRoutePath, '', url);

[tommycli, 2016/08/10 22:15:28]

Yeah. That would be cleaner. Changed.

     setCurrentRoute(route, params);
-    window.history.pushState(undefined, '', url);
+    window.history.pushState(state, '', url);
   };
 
   window.addEventListener('popstate', function(event) {