MD Settings: Fix initialization timing of browser proxy in change-picture.

chrome/browser/resources/settings/people_page/change_picture.js

Index: chrome/browser/resources/settings/people_page/change_picture.js
diff --git a/chrome/browser/resources/settings/people_page/change_picture.js b/chrome/browser/resources/settings/people_page/change_picture.js
index 96ad5c23a5624ef5de5e87f7a71c29fb2f049f1b..62c5b9dad7979d41948025deaa39cc9a707a9089 100644
--- a/chrome/browser/resources/settings/people_page/change_picture.js
+++ b/chrome/browser/resources/settings/people_page/change_picture.js
@@ -114,8 +114,12 @@ Polymer({
   lastSelectedImageType_: '',
 
   /** @override */
-  attached: function() {
+  ready: function() {
     this.browserProxy_ = settings.ChangePictureBrowserProxyImpl.getInstance();
+  },
+
+  /** @override */
+  attached: function() {
     this.addWebUIListener('default-images-changed',
                           this.receiveDefaultImages_.bind(this));
     this.addWebUIListener('selected-image-changed',