Customizer: Export nonce, theme, and url app settings in preview as exported in pane.

* Introduce `WP_Customize_Manager::get_nonces()` to consolidate logic for retrieving nonces.
* Export nonces centrally in `wp.customize.settings.nonce` with each request and update nav menus preview to utilize.
* Send updated nonces to preview upon `nonce-refresh`.
* Request full preview refresh if Nav Menu selective refresh request fails (e.g. due to bad nonce).
* Update nav menus and widgets in Customizer to utilize `customize_refresh_nonces` for exporting nonces and keeping them up to date.

See #27355.
Fixes #35617.


git-svn-id: https://develop.svn.wordpress.org/trunk@36414 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/js/customize-controls.js

@@ -3375,6 +3375,7 @@
 		api.bind( 'nonce-refresh', function( nonce ) {
 			$.extend( api.settings.nonce, nonce );
 			$.extend( api.previewer.nonce, nonce );
+			api.previewer.send( 'nonce-refresh', nonce );
 		});
 
 		// Create Settings

src/wp-admin/js/customize-nav-menus.js

@@ -323,7 +323,7 @@
 			availableMenuItemContainer.find( '.accordion-section-title' ).addClass( 'loading' );
 			self.loading = true;
 			params = {
-				'customize-menus-nonce': api.Menus.data.nonce,
+				'customize-menus-nonce': api.settings.nonce['customize-menus'],
 				'wp_customize': 'on',
 				'type': type,
 				'object': object,

src/wp-admin/js/customize-widgets.js

@@ -1107,7 +1107,7 @@
 			params = {};
 			params.action = 'update-widget';
 			params.wp_customize = 'on';
-			params.nonce = api.Widgets.data.nonce;
+			params.nonce = api.settings.nonce['update-widget'];
 			params.theme = api.settings.theme.stylesheet;
 			params.customized = wp.customize.previewer.query().customized;
 
@@ -2058,11 +2058,6 @@
 		sidebar_widgets: api.Widgets.SidebarControl
 	});
 
-	// Refresh the nonce if login sends updated nonces over.
-	api.bind( 'nonce-refresh', function( nonces ) {
-		api.Widgets.data.nonce = nonces['update-widget'];
-	});
-
 	/**
 	 * Init Customizer for widgets.
 	 */