Fix a typo in UserScript comment.

chrome/common/extensions/user_script.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_EXTENSIONS_USER_SCRIPT_H_
 #define CHROME_COMMON_EXTENSIONS_USER_SCRIPT_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 19 matching lines @@
   // extension.
   static bool IsURLUserScript(const GURL& url, const std::string& mime_type);
 
   // Get the valid user script schemes for the current process. If
   // canExecuteScriptEverywhere is true, this will return ALL_SCHEMES.
   static int ValidUserScriptSchemes(bool canExecuteScriptEverywhere = false);
 
   // Locations that user scripts can be run inside the document.
   enum RunLocation {
     UNDEFINED,
-    DOCUMENT_START,  // After the documentElemnet is created, but before
+    DOCUMENT_START,  // After the documentElement is created, but before
                      // anything else happens.
     DOCUMENT_END,  // After the entire document is parsed. Same as
                    // DOMContentLoaded.
     DOCUMENT_IDLE,  // Sometime after DOMContentLoaded, as soon as the document
                     // is "idle". Currently this uses the simple heuristic of:
                     // min(DOM_CONTENT_LOADED + TIMEOUT, ONLOAD), but no
                     // particular injection point is guaranteed.
     RUN_LOCATION_LAST  // Leave this as the last item.
   };
 
@@ skipping 200 matching lines @@
 
   // True if the script should be injected into an incognito tab.
   bool incognito_enabled_;
 };
 
 typedef std::vector<UserScript> UserScriptList;
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_USER_SCRIPT_H_