PPAPI: header comments on when PPP_Instance::DidDestroy and PPP_ShutdownModule

ppapi/api/ppp_instance.idl

 /* Copyright (c) 2011 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 <code>PPP_Instance</code> structure - a series of
  * pointers to methods that you must implement in your module.
  */
 
@@ skipping 71 matching lines @@
    * DidDestroy() is an instance destruction handler. This function is called
    * in many cases (see below) when a module instance is destroyed. It will be
    * called even if DidCreate() returned failure.
    *
    * Generally you will handle this call by deallocating the tracking
    * information and the <code>PP_Instance</code> mapping you created in the
    * DidCreate() call. You can also free resources associated with this
    * instance but this isn't required; all resources associated with the deleted
    * instance will be automatically freed when this function returns.
    *
-   * The instance identifier will still be valid during this call so the module
+   * The instance identifier will still be valid during this call, so the module
    * can perform cleanup-related tasks. Once this function returns, the
    * <code>PP_Instance</code> handle will be invalid. This means that you can't
-   * do any asynchronous operations like network requests or file writes from
-   * this function since they will be immediately canceled.
+   * do any asynchronous operations like network requests, file writes or
+   * messaging from this function since they will be immediately canceled.
    *
-   * <strong>Note:</strong> This function may be skipped in certain
-   * circumstances when Chrome does "fast shutdown". Fast shutdown will happen
-   * in some cases when all module instances are being deleted, and no cleanup
-   * functions will be called. The module will just be unloaded and the process
-   * terminated.
+   * <strong>Note:</strong> This function will always be skipped on untrusted
+   * (Native Client) implementations. This function may be skipped on trusted
+   * implementations in certain circumstances when Chrome does "fast shutdown"
+   * of a web page. Fast shutdown will happen in some cases when all module
+   * instances are being deleted, and no cleanup functions will be called.
+   * The module will just be unloaded and the process terminated.
    *
    * @param[in] instance A <code>PP_Instance</code> indentifying one instance
    * of a module.
    */
   void DidDestroy(
       /* A PP_Instance indentifying one instance of a module. */
       [in] PP_Instance instance);
 
   /**
    * DidChangeView() is called when the position, the size, of the clip
@@ skipping 101 matching lines @@
       [in] PP_Resource url_loader);
 
 };
 
 #inline c
 
 typedef struct PPP_Instance PPP_Instance_1_0;
 
 #endinl