Set up serving infrastructure for c/b/r/settings.

chrome/browser/resources/settings/prefs/prefs.js

Index: chrome/browser/resources/settings/prefs/prefs.js
diff --git a/chrome/browser/resources/settings/prefs/prefs.js b/chrome/browser/resources/settings/prefs/prefs.js
index a50dd7f9852e8b54892725b0cae13f7d54a66405..10abcdba9ba170d0519becb00d4e7dbb60ec2b5d 100644
--- a/chrome/browser/resources/settings/prefs/prefs.js
+++ b/chrome/browser/resources/settings/prefs/prefs.js
@@ -75,6 +75,18 @@ Polymer('cr-settings-prefs', {
     // TODO(jlklein): Actually pull the data out of prefs and initialize.
   },
 
+   /**
+   * Converts a camel-case property name to the prefs underscore format.
+   * @param {string} camelCaseName
+   * @return {string} The name with underscores instead of dashes.
+   * @private
+   */
+  camelCaseToUnderscores_: function(camelCaseName) {
+    return camelCaseName.replace(/([A-Z])/g, function($1) {
+      return '_' + $1.toLowerCase();
+    });
+  },
+
   /**
    * @param {string} propertyPath The path before the property names.
    * @param {!Array<string>} added An array of keys which were added.
@@ -88,12 +100,14 @@ Polymer('cr-settings-prefs', {
   propertyChangeCallback_: function(
       propertyPath, added, removed, changed, getOldValueFn) {
     Object.keys(changed).forEach(function(property) {
+      var pref = this.camelCaseToUnderscores_(`${propertyPath}.${property}`);
+      var value = changed[property];
       console.log(
-          `${propertyPath}.${property}`,
+          pref,
           `old : ${getOldValueFn(property)}`,
-          `newValue : ${changed[property]}`);
+          `newValue : ${value}`);
 
       // TODO(jlklein): Actually set the changed property back to prefs.
-    });
+    }.bind(this));
    },
 });