(defun mayoff:open-url-in-chrome (url)
  "Open URL in Google Chrome.  I use AppleScript to do several things:
  1. I tell Chrome to come to the front. If Chrome wasn't launched, this will also launch it.
  2. If Chrome has no windows open, I tell it to create one.
  3. If Chrome has a tab showing URL, I tell it to reload the tab, make that tab the active tab in its window, and bring its window to the front.
  4. If Chrome has no tab showing URL, I tell Chrome to make a new tab (in the front window) showing URL."
  (when (symbolp url)
    ; User passed a symbol instead of a string.  Use the symbol name.
    (setq url (symbol-name url)))
  (do-applescript (format "
tell application \"Google Chrome\"
	activate
	set theUrl to %S
	
	if (count every window) = 0 then
		make new window
	end if
	
	set found to false
	set theTabIndex to -1
	repeat with theWindow in every window
		set theTabIndex to 0
		repeat with theTab in every tab of theWindow
			set theTabIndex to theTabIndex + 1
			if theTab's URL = theUrl then
				set found to true
				exit
			end if
		end repeat
		
		if found then
			exit repeat
		end if
	end repeat
	
	if found then
		tell theTab to reload
		set theWindow's active tab index to theTabIndex
		set index of theWindow to 1
	else
		tell window 1 to make new tab with properties {URL:theUrl}
	end if
end tell
  " url)))

(defvar mayoff:open-in-chrome-url nil
  "*The URL that the mayoff:open-in-chrome function will send to Google Chrome.")

(defun mayoff:open-in-chrome (arg)
  "Open or reload a file in Google Chrome.  If you give me a prefix argument, I get Chrome's currently-displayed URL and save it for the future.  If you don't give me a prefix argument, I send the previously-saved URL to Chrome for reloading."
  (interactive "P")
  (cond
   (arg (setq mayoff:open-in-chrome-url (do-applescript "tell application \"Google Chrome\" to get window 1's active tab's URL")))
   ((not mayoff:open-in-chrome-url) (error "You haven't set a URL for me to send to the browser."))
   (t (save-buffer)
      (mayoff:open-url-in-chrome mayoff:open-in-chrome-url))))

(global-set-key (kbd "<f5>") 'mayoff:open-in-chrome)