[PPAPI] Fix a bunch of spelling mistakes

ppapi/api/ppb_url_loader.idl

 /* 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.
  */
 
 /**
  * This file defines the <strong>PPB_URLLoader</strong> interface for loading
  * URLs.
  */
 
@@ skipping 53 matching lines @@
    * Open() begins loading the <code>URLRequestInfo</code>. The operation
    * completes when response headers are received or when an error occurs.  Use
    * GetResponseInfo() to access the response headers.
    *
    * @param[in] loader A <code>PP_Resource</code> corresponding to a
    * <code>URLLoader</code>.
    * @param[in] resource A <code>PP_Resource</code> corresponding to a
    * <code>URLRequestInfo</code>.
    * @param[in] callback A <code>PP_CompletionCallback</code> to run on
    * asynchronous completion of Open(). This callback will run when response
-   * headers for the url are received or error occured. This callback
+   * headers for the url are received or error occurred. This callback
    * will only run if Open() returns <code>PP_OK_COMPLETIONPENDING</code>.
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
    */
   int32_t Open(
       [in] PP_Resource loader,
       [in] PP_Resource request_info,
       [in] PP_CompletionCallback callback);
 
   /**
@@ skipping 127 matching lines @@
    * while it is still open, then it will be implicitly closed so you are not
    * required to call Close().
    *
    * @param[in] loader A <code>PP_Resource</code> corresponding to a
    * <code>URLLoader</code>.
    */
   void Close(
       [in] PP_Resource loader);
 };