[PPAPI] Fix a bunch of spelling mistakes

ppapi/api/ppb_message_loop.idl

Index: ppapi/api/ppb_message_loop.idl
diff --git a/ppapi/api/ppb_message_loop.idl b/ppapi/api/ppb_message_loop.idl
index 5ae00b128a15e6f02a52af95604980b43061cffb..fad873a45b4f67842d019e49109be26eadd8b5c5 100644
--- a/ppapi/api/ppb_message_loop.idl
+++ b/ppapi/api/ppb_message_loop.idl
@@ -23,7 +23,7 @@ label Chrome {
  * suddenly see their PP_Resource handles become invalid. In this case, calls
  * will fail with PP_ERROR_BADRESOURCE. If you need to access data associated
  * with your instance, you will probably want to create some kind of threadsafe
- * proxy object that can handle asynchonous destruction of the instance object.
+ * proxy object that can handle asynchronous destruction of the instance object.
  *
  * Typical usage:
  *   On the main thread:
@@ -36,7 +36,7 @@ label Chrome {
  *    - Call AttachToCurrentThread() with the message loop resource.
  *    - Call Run() with the message loop resource.
  *
- *   Your callacks should look like this:
+ *   Your callbacks should look like this:
  *      void DoMyWork(void* user_data, int32_t status) {
  *        if (status != PP_OK) {
  *          Cleanup();  // e.g. free user_data.
@@ -206,7 +206,7 @@ interface PPB_MessageLoop {
    *
    * @param callback The completion callback to execute from the message loop.
    *
-   * @param delay_ms The number of millseconds to delay execution of the given
+   * @param delay_ms The number of milliseconds to delay execution of the given
    * completion callback. Passing 0 means it will get queued normally and
    * executed in order.
    *
@@ -221,7 +221,7 @@ interface PPB_MessageLoop {
    * run your callback with an error without causing unexpected threading
    * problems). If you associate memory with the completion callback (for
    * example, you're using the C++ CompletionCallbackFactory), you will need to
-   * free this or manually run the callback. See "Desctruction and error
+   * free this or manually run the callback. See "Destruction and error
    * handling" above.
    *
    *