Real-time collaboration: Slash meta key/values for updates and deletes.

Slashes the meta key and meta values when adding or deleting meta data in the `WP_Sync_Post_Meta_Storage` class for real time collaboration.

Props peterwilsoncc, westonruter.
Fixes #64783.


git-svn-id: https://develop.svn.wordpress.org/trunk@61788 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-includes/collaboration/class-wp-sync-post-meta-storage.php

@@ -85,7 +85,7 @@ public function add_update( string $room, $update ): bool {
 			'value'     => $update,
 		);
 
-		return (bool) add_post_meta( $post_id, self::SYNC_UPDATE_META_KEY, $envelope, false );
+		return (bool) add_post_meta( $post_id, wp_slash( self::SYNC_UPDATE_META_KEY ), wp_slash( $envelope ), false );
 	}
 
 	/**
@@ -162,7 +162,7 @@ public function set_awareness_state( string $room, array $awareness ): bool {
 		}
 
 		// update_post_meta returns false if the value is the same as the existing value.
-		update_post_meta( $post_id, self::AWARENESS_META_KEY, $awareness );
+		update_post_meta( $post_id, wp_slash( self::AWARENESS_META_KEY ), wp_slash( $awareness ) );
 		return true;
 	}
 
@@ -305,7 +305,7 @@ public function remove_updates_before_cursor( string $room, int $cursor ): bool
 		$all_updates = $this->get_all_updates( $room );
 
 		// Remove all updates for the room and re-store only those that are newer than the cursor.
-		if ( ! delete_post_meta( $post_id, self::SYNC_UPDATE_META_KEY ) ) {
+		if ( ! delete_post_meta( $post_id, wp_slash( self::SYNC_UPDATE_META_KEY ) ) ) {
 			return false;
 		}