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

Bug: 747596
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I28e93a4b0be176718df12048fed66e4d696bd4de
Reviewed-on: https://chromium-review.googlesource.com/597111Reviewed-by: Dave Schuyler <dschuyler@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491535}

chrome/browser/resources/md_user_manager/control_bar.js

@@ -52,14 +52,14 @@ Polymer({
    * @private
    */
   onLaunchGuestTap_: function(event) {
-    this.browserProxy_.areAllProfilesLocked().then(function(allProfilesLocked) {
+    this.browserProxy_.areAllProfilesLocked().then(allProfilesLocked => {
       if (!allProfilesLocked || this.isForceSigninEnabled_) {
         this.browserProxy_.launchGuestUser();
       } else {
         document.querySelector('error-dialog')
             .show(this.i18n('browseAsGuestAllProfilesLockedError'));
       }
-    }.bind(this));
+    });
   },
 
   /**
@@ -68,7 +68,7 @@ Polymer({
    * @private
    */
   onAddUserTap_: function(event) {
-    this.browserProxy_.areAllProfilesLocked().then(function(allProfilesLocked) {
+    this.browserProxy_.areAllProfilesLocked().then(allProfilesLocked => {
       if (!allProfilesLocked || this.isForceSigninEnabled_) {
         // Event is caught by user-manager-pages.
         this.fire('change-page', {page: 'create-user-page'});
@@ -76,6 +76,6 @@ Polymer({
         document.querySelector('error-dialog')
             .show(this.i18n('addProfileAllProfilesLockedError'));
       }
-    }.bind(this));
+    });
   }
 });

chrome/browser/resources/md_user_manager/create_profile.js

@@ -154,9 +154,9 @@ Polymer({
         'create-profile-warning', this.handleMessage_.bind(this));
     this.addWebUIListener(
         'create-profile-error', this.handleMessage_.bind(this));
-    this.addWebUIListener('profile-icons-received', function(icons) {
+    this.addWebUIListener('profile-icons-received', icons => {
       this.availableIcons_ = icons;
-    }.bind(this));
+    });
     this.addWebUIListener(
         'profile-defaults-received', this.handleProfileDefaults_.bind(this));
     this.addWebUIListener(