Index: wp-includes/vars.php
===================================================================
--- wp-includes/vars.php	(revision 15646)
+++ wp-includes/vars.php	(working copy)
@@ -35,12 +35,13 @@
 }
 
 // Simple browser detection
-$is_lynx = $is_gecko = $is_winIE = $is_macIE = $is_opera = $is_NS4 = $is_safari = $is_chrome = $is_iphone = false;
+$is_lynx = $is_gecko = $is_winIE = $is_macIE = $is_opera = $is_NS4 = $is_safari = $is_chrome = $is_iphone = $is_chromeframe = false;
 
 if ( isset($_SERVER['HTTP_USER_AGENT']) ) {
+	$is_chromeframe = false !== strpos($_SERVER['HTTP_USER_AGENT'], 'chromeframe');
 	if ( strpos($_SERVER['HTTP_USER_AGENT'], 'Lynx') !== false ) {
 		$is_lynx = true;
-	} elseif ( stripos($_SERVER['HTTP_USER_AGENT'], 'chrome') !== false ) {
+	} elseif ( stripos($_SERVER['HTTP_USER_AGENT'], 'chrome') !== false && $is_chromeframe === false ) {
 		$is_chrome = true;
 	} elseif ( stripos($_SERVER['HTTP_USER_AGENT'], 'safari') !== false ) {
 		$is_safari = true;
@@ -62,6 +63,10 @@
 
 $is_IE = ( $is_macIE || $is_winIE );
 
+// Google Chrome Frame Support
+if ( $is_chromeframe && apply_filters( 'use_google_chrome_frame', is_admin() ) )
+		header('X-UA-Compatible: chrome=1');
+
 // Server detection
 
 /**