Index: wp-includes/class-wp.php
===================================================================
--- wp-includes/class-wp.php	(revision 44451)
+++ wp-includes/class-wp.php	(working copy)
@@ -388,6 +388,20 @@
 	}
 
 	/**
+	 * Allow performing actions based on the blocks in the content.
+	 *
+	 * This allows plugins and themes to send headers or enqueue styles and scripts based on the blocks in the
+	 * current page.
+	 *
+	 * @since 5.2
+	 */
+	public function parse_blocks() {
+		if ( is_singular() ) {
+			do_action( 'parsed_blocks', parse_blocks( get_the_content() ) );
+		}
+	}
+
+	/**
 	 * Sends additional HTTP headers for caching, content type, etc.
 	 *
 	 * Sets the Content-Type header. Sets the 'error' status (if passed) and optionally exits.
@@ -735,6 +749,7 @@
 	public function main( $query_args = '' ) {
 		$this->init();
 		$this->parse_request( $query_args );
+		$this->parse_blocks();
 		$this->send_headers();
 		$this->query_posts();
 		$this->handle_404();