PPAPI: Make blocking completion callbacks work.

ppapi/shared_impl/private/ppb_host_resolver_shared.cc

 // 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.
 
 #include "ppapi/shared_impl/private/ppb_host_resolver_shared.h"
 
 #include <cstddef>
 #include <cstring>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 35 matching lines @@
 
 thunk::PPB_HostResolver_Private_API*
 PPB_HostResolver_Shared::AsPPB_HostResolver_Private_API() {
   return this;
 }
 
 int32_t PPB_HostResolver_Shared::Resolve(
     const char* host,
     uint16_t port,
     const PP_HostResolver_Private_Hint* hint,
-    PP_CompletionCallback callback) {
+    scoped_refptr<TrackedCallback> callback) {
   if (!host)
     return PP_ERROR_BADARGUMENT;
-  if (!callback.func)
-    return PP_ERROR_BLOCKS_MAIN_THREAD;
   if (ResolveInProgress())
     return PP_ERROR_INPROGRESS;
 
-  resolve_callback_ = new TrackedCallback(this, callback);
+  resolve_callback_ = callback;
 
   HostPortPair host_port;
   host_port.host = host;
   host_port.port = port;
 
   SendResolve(host_port, hint);
   return PP_OK_COMPLETIONPENDING;
 }
 
 PP_Var PPB_HostResolver_Shared::GetCanonicalName() {
@@ skipping 33 matching lines @@
 uint32 PPB_HostResolver_Shared::GenerateHostResolverID() {
   static uint32 host_resolver_id = 0;
   return host_resolver_id++;
 }
 
 bool PPB_HostResolver_Shared::ResolveInProgress() const {
   return TrackedCallback::IsPending(resolve_callback_);
 }
 
 }  // namespace ppapi