Add initial support for "foreground" command

This is mainly for the benefit of Chromebooks who have a chroot'ed emacs that can run on the main display window. When enabled the /foreground command will make emacs pop up in the front of the display without an edit buffer when there is no text area in focus and the button is clicked.

edit-server.el

@@ -195,6 +195,11 @@ Depending on the character encoding, may be different from the buffer length.")
 (make-variable-buffer-local 'edit-server-request)
 (put 'edit-server-request 'permanent-local t)
 
+(defvar edit-server-request-url nil
+  "The HTTP request URL received.")
+(make-variable-buffer-local 'edit-server-request-url)
+(put 'edit-server-request-url 'permanent-local t)
+
 (defvar edit-server-content-length nil
   "The value gotten from the HTTP `Content-Length' header.")
 (make-variable-buffer-local 'edit-server-content-length)
@@ -357,7 +362,8 @@ non-nil, then STRING is also echoed to the message line."
     (with-current-buffer buffer
       (setq edit-server-phase 'wait
 	    edit-server-received 0
-	    edit-server-request nil))
+	    edit-server-request nil
+	    edit-server-request-url nil))
     (setq edit-server-content-length nil
 	  edit-server-url nil
 	  edit-server-file nil))
@@ -381,12 +387,13 @@ non-nil, then STRING is also echoed to the message line."
 	(when (re-search-forward
 	       "^\\([A-Z]+\\)\\s-+\\(\\S-+\\)\\s-+\\(HTTP/[0-9\.]+\\)\r?\n"
 	       nil t)
+	  (setq edit-server-request (match-string 1)
+		edit-server-request-url (match-string 2)
+		edit-server-content-length nil
+		edit-server-phase 'head)
 	  (edit-server-log
-	   proc "Got HTTP `%s' request, processing in buffer `%s'..."
-	   (match-string 1) (current-buffer))
-	  (setq edit-server-request (match-string 1))
-	  (setq edit-server-content-length nil)
-	  (setq edit-server-phase 'head))))
+	   proc "Got HTTP `%s' request of url `%s', processing in buffer `%s'..."
+	   edit-server-request edit-server-request-url (current-buffer)))))
 
     (when (eq edit-server-phase 'head)
       ;; look for "Content-length" header
@@ -432,6 +439,10 @@ non-nil, then STRING is also echoed to the message line."
 	 ((string= edit-server-request "POST")
 	  ;; create editing buffer, and move content to it
 	  (edit-server-find-or-create-edit-buffer proc edit-server-file))
+	 ((string-match "foreground" edit-server-request-url)
+	  (edit-server-foreground-request)
+	  (edit-server-send-response proc "edit-server received foreground request.\n")
+	  (edit-server-kill-client proc))
 	 (t
 	  ;; send 200 OK response to any other request
 	  (edit-server-send-response proc "edit-server is running.\n")
@@ -440,6 +451,12 @@ non-nil, then STRING is also echoed to the message line."
 	(setq edit-server-received 0)
 	(setq edit-server-phase 'wait)))))
 
+(defun edit-server-foreground-request ()
+  "Bring Emacs into the foreground after a request from Chrome"
+  (when edit-server-new-frame
+    (make-frame-on-display (getenv "DISPLAY")
+			   edit-server-new-frame-alist)))
+
 (defun edit-server-show-edit-buffer (buffer)
   "Show edit buffer by creating a frame or raising the selected
 frame."