--- /Applications/Emacs.app/Contents/Resources/lisp/arc-mode.el 2011-01-09 00:14:24.000000000 -0800
+++ crx-arc-mode.el 2011-01-09 00:20:00.000000000 -0800
@@ -694,6 +694,7 @@
   ;; as an archive by other software.
   (let (case-fold-search)
     (cond ((looking-at "[P]K\003\004") 'zip)
+     ((looking-at "Cr24") 'zip)
      ((looking-at "..-l[hz][0-9ds]-") 'lzh)
      ((looking-at "....................[\334]\247\304\375") 'zoo)
      ((and (looking-at "\C-z") ; signature too simple, IMHO
@@ -1021,7 +1022,7 @@
   (apply 'call-process
     (car command)
     nil
-    t
+    '(t nil) ;;; stdout to current buffer, stderr to /dev/null
     nil
     (append (cdr command) (list archive name))))

@@ -1659,7 +1660,17 @@
 (defun archive-zip-summarize ()
   (goto-char (- (point-max) (- 22 18)))
   (search-backward-regexp "[P]K\005\006")
-  (let ((p (+ (point-min) (archive-l-e (+ (point) 16) 4)))
+  ;;; Google Chrome Extensions prepend a 16 bytes + pubkey + signature header to
+  ;;; an otherwise zip:y file: http://code.google.com/chrome/extensions/crx.html
+  (let ((p (+ (point-min)
+              ;;; if a Google Chrome extension, add its leading header block:
+              (if (string-equal "Cr24" (buffer-substring (point-min)
+                                                         (+ (point-min) 4)))
+                  (+ 16                                  ;;; Chrome header
+                     (archive-l-e (+ (point-min) 8) 4)   ;;; pubkey length
+                     (archive-l-e (+ (point-min) 12) 4)) ;;; signature length
+                0) ; no -- not a Google Chrome extension
+              (archive-l-e (+ (point) 16) 4)))
         (maxlen 8)
    (totalsize 0)
         files