WebSocket Pepper API: fix data corruption at ReceiveMessage in NaCl

ppapi/native_client/src/shared/ppapi_proxy/browser_callback.cc

Index: ppapi/native_client/src/shared/ppapi_proxy/browser_callback.cc
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/browser_callback.cc b/ppapi/native_client/src/shared/ppapi_proxy/browser_callback.cc
index 5f5e7c36e8df810bfb20b1b652f90d43c4fedf3e..6849a8e8db44acb42f1b1d264b7799c9a4492ee6 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/browser_callback.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/browser_callback.cc
@@ -136,6 +136,12 @@ struct PP_CompletionCallback MakeRemoteCompletionCallback(
   if (var)
     *var = &remote_callback->read_var;
 
+  // If caller requires to copy data at completion, the callback must be
+  // asynchronous. Because the copy is performed in RunRemoteCallback.
+  if ((bytes_to_read > 0 && buffer != NULL) || var)
+    return PP_MakeCompletionCallback(
+        RunRemoteCallback, remote_callback.release());

[dmichael (off chromium), 2012/03/21 19:16:47]

This is going to affect URLLoader::ReadResponseBody, which is designed to
correctly handle an optional callback.

I think it would be better to either:
(a) Make your code also handle the optional case (this would be the best
performing approach, though possibly complicated. You can see the way URLLoader
does it for an example)
(b) Clear the "optional" flag after you get the result from
MakeRemoteCompletionCallback (with appropriate documentation there). This is
probably the simplest way to go, but you won't get as good of performance.

+
   return PP_MakeOptionalCompletionCallback(
       RunRemoteCallback, remote_callback.release());
 }