Support using TrackedCallbacks as hints to determine the handling thread of resource reply messages

ppapi/proxy/resource_reply_thread_registrar.cc

+// Copyright (c) 2013 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/proxy/resource_reply_thread_registrar.h"
+
+#include "base/message_loop/message_loop_proxy.h"
+#include "ppapi/shared_impl/proxy_lock.h"
+
+namespace ppapi {
+namespace proxy {
+
+ResourceReplyThreadRegistrar::ResourceReplyThreadRegistrar(
+    scoped_refptr<base::MessageLoopProxy> default_thread)
+    : default_thread_(default_thread) {
+}
+
+ResourceReplyThreadRegistrar::~ResourceReplyThreadRegistrar() {
+}
+
+void ResourceReplyThreadRegistrar::Register(
+    PP_Resource resource,
+    int32_t sequence_number,
+    scoped_refptr<TrackedCallback> reply_thread_hint) {
+  ProxyLock::AssertAcquiredDebugOnly();
+
+  // TODO(yzshen): add comments.

[dmichael (off chromium), 2013/12/11 21:30:36]

Would be good to add the comments before checking in ^^^

[yzshen1, 2013/12/11 22:22:07]

This is an old patchset. Please see the latest one.
On 2013/12/11 21:30:36, dmichael wrote:

+  if (!reply_thread_hint || reply_thread_hint->is_blocking())
+    return;
+
+  DCHECK(reply_thread_hint->target_loop());
+  scoped_refptr<base::MessageLoopProxy> reply_thread(
+      reply_thread_hint->target_loop()->GetMessageLoopProxy());
+  {
+    base::AutoLock auto_lock(lock_);
+
+    if (reply_thread == default_thread_)
+      return;
+
+    map_[resource][sequence_number] = reply_thread;
+  }
+}
+
+void ResourceReplyThreadRegistrar::Unregister(PP_Resource resource) {
+  base::AutoLock auto_lock(lock_);
+  map_.erase(resource);
+}
+
+scoped_refptr<base::MessageLoopProxy>
+ResourceReplyThreadRegistrar::GetTargetThread(
+    PP_Resource resource,
+    int32_t sequence_number) {
+  base::AutoLock auto_lock(lock_);
+  ResourceMap::iterator resource_iter = map_.find(resource);
+  if (resource_iter == map_.end())
+    return default_thread_;
+
+  SequenceNumberMap::iterator sequence_number_iter =
+      resource_iter->second.find(sequence_number);
+  if (sequence_number_iter == resource_iter->second.end())
+    return default_thread_;
+
+  scoped_refptr<base::MessageLoopProxy> target = sequence_number_iter->second;
+  resource_iter->second.erase(sequence_number_iter);
+  return target;
+}
+
+}  // namespace proxy
+}  // namespace ppapi