General: Account for `Sec-CH-UA-Mobile` client hint request header in `wp_is_mobile()`.

Add missing test coverage for `wp_is_mobile()`.

Fixes #59370.
Props westonruter, flixos90.

Built from https://develop.svn.wordpress.org/trunk@56638


git-svn-id: http://core.svn.wordpress.org/trunk@56150 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/vars.php

@@ -144,11 +144,16 @@ $is_iis7 = $is_IIS && (int) substr( $_SERVER['SERVER_SOFTWARE'], strpos( $_SERVE
  * Test if the current browser runs on a mobile device (smart phone, tablet, etc.)
  *
  * @since 3.4.0
+ * @since 6.4.0 Added checking for the Sec-CH-UA-Mobile request header.
  *
  * @return bool
  */
 function wp_is_mobile() {
-	if ( empty( $_SERVER['HTTP_USER_AGENT'] ) ) {
+	if ( isset( $_SERVER['HTTP_SEC_CH_UA_MOBILE'] ) ) {
+		// This is the `Sec-CH-UA-Mobile` user agent client hint HTTP request header.
+		// See <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-UA-Mobile>.
+		$is_mobile = ( '?1' === $_SERVER['HTTP_SEC_CH_UA_MOBILE'] );
+	} elseif ( empty( $_SERVER['HTTP_USER_AGENT'] ) ) {
 		$is_mobile = false;
 	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Mobile' ) // Many mobile devices (all iPhone, iPad, etc.)
 		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'Android' )

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56637';
+$wp_version = '6.4-alpha-56638';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.