Add a new error code for a null callback on the main thread.

Convert the NaCl and ChromeIPC proxies to use the new value.

Review URL: http://codereview.chromium.org/7885014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@101556 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 29 insertions, 3 deletions

diff --git a/ppapi/api/pp_errors.idl b/ppapi/api/pp_errors.idl
index 950b77b..bd49081 100644
--- a/ppapi/api/pp_errors.idl
+++ b/ppapi/api/pp_errors.idl
@@ -9,7 +9,10 @@
 
 /**
  * This enumeration contains enumerators of all PPAPI error codes.
- * Errors are negative valued.
+ *
+ * Errors are negative valued. Callers should treat all negative values as a
+ * failure, even if it's not in the list, since the possible errors are likely
+ * to expand and change over time.
  */
 [unnamed] enum PP_Error {
   /**
@@ -26,11 +29,20 @@
    */
   PP_OK_COMPLETIONPENDING = -1,
 
-  /** This value indicates failure for unspecified reasons. */
+  /**This value indicates failure for unspecified reasons. */
   PP_ERROR_FAILED         = -2,
+
   /**
    * This value indicates failure due to an asynchronous operation being
-   * interrupted, typically as a result of user action.
+   * interrupted. The most common cause of this error code is destroying a
+   * resource that still has a callback pending. All callbacks are guaranteed
+   * to execute, so any callbacks pending on a destroyed resource will be
+   * issued with PP_ERROR_ABORTED.
+   *
+   * If you get an aborted notification that you aren't expecting, check to
+   * make sure that the resource you're using is still in scope. A common
+   * mistake is to create a resource on the stack, which will destroy the
+   * resource as soon as the function returns.
    */
   PP_ERROR_ABORTED        = -3,
 
@@ -67,6 +79,20 @@
    */
   PP_ERROR_NOTSUPPORTED = -12,
 
+  /**
+   * Returned if you try to use a null completion callback to "block until
+   * complete" on the main thread. Blocking the main thread is not permitted
+   * to keep the browser responsive (otherwise, you may not be able to handle
+   * input events, and there are reentrancy and deadlock issues).
+   *
+   * The goal is to provide blocking calls from background threads, but PPAPI
+   * calls on background threads are not currently supported. Until this
+   * support is complete, you must either do asynchronous operations on the
+   * main thread, or provide an adaptor for a blocking background thread to
+   * execute the operaitions on the main thread.
+   */
+  PP_ERROR_BLOCKS_MAIN_THREAD = -13,
+
   PP_ERROR_FILENOTFOUND   = -20,
   /** This value indicates failure due to a file that already exists. */
   PP_ERROR_FILEEXISTS     = -21,