MD Settings: Convert all usages of .bind(this) to use ES6 arrow function.

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

Index: chrome/browser/resources/settings/people_page/people_page.js
diff --git a/chrome/browser/resources/settings/people_page/people_page.js b/chrome/browser/resources/settings/people_page/people_page.js
index 35b743b750f967d36dc8d6fe959a65137355e696..dcc6b531cb89ead2b1e0875f0d814ed6182c6297 100644
--- a/chrome/browser/resources/settings/people_page/people_page.js
+++ b/chrome/browser/resources/settings/people_page/people_page.js
@@ -163,9 +163,9 @@ Polymer({
         settings.navigateToPreviousRoute();
       } else {
         this.showDisconnectDialog_ = true;
-        this.async(function() {
+        this.async(() => {
           this.$$('#disconnectDialog').showModal();
-        }.bind(this));
+        });
       }
     } else if (this.showDisconnectDialog_) {
       this.$$('#disconnectDialog').close();
@@ -291,9 +291,9 @@ Polymer({
     // browser is closed after the sign out. Otherwise, the navigation will be
     // finshed during session restore if the browser is closed before the async
     // callback executed.
-    listenOnce(this, 'signout-dialog-closed', function() {
+    listenOnce(this, 'signout-dialog-closed', () => {
       this.syncBrowserProxy_.signOut(deleteProfile);
-    }.bind(this));
+    });
 
     this.$$('#disconnectDialog').close();
   },