Add IPC::ForwardingMessageFilter.

ipc/ipc_forwarding_message_filter.cc

Index: ipc/ipc_forwarding_message_filter.cc
diff --git a/ipc/ipc_forwarding_message_filter.cc b/ipc/ipc_forwarding_message_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..48f6e5ff810dbd14fa9afe2f98901098bbb3b986
--- /dev/null
+++ b/ipc/ipc_forwarding_message_filter.cc
@@ -0,0 +1,60 @@
+// 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 "ipc/ipc_forwarding_message_filter.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+
+namespace IPC {
+
+ForwardingMessageFilter::ForwardingMessageFilter(
+    const uint32* message_ids_to_filter,
+    size_t num_message_ids_to_filter,
+    base::TaskRunner* target_task_runner,
+    const Handler& handler)
+    : target_task_runner_(target_task_runner),
+      handler_(handler) {
+  DCHECK(target_task_runner_);
+  DCHECK(!handler_.is_null());
+  for (size_t i = 0; i < num_message_ids_to_filter; i++)
+    message_ids_to_filter_.insert(message_ids_to_filter[i]);
+}
+
+void ForwardingMessageFilter::AddRoute(int routing_id) {
+  base::AutoLock locked(routes_lock_);
+  routes_.insert(routing_id);
+}
+
+void ForwardingMessageFilter::RemoveRoute(int routing_id) {
+  base::AutoLock locked(routes_lock_);
+  routes_.erase(routing_id);
+}
+
+bool ForwardingMessageFilter::OnMessageReceived(const Message& message) {
+  if (message_ids_to_filter_.find(message.type()) ==
+      message_ids_to_filter_.end())
+    return false;
+
+  {
+    base::AutoLock locked(routes_lock_);
+    if (routes_.find(message.routing_id()) == routes_.end())
+      return false;
+  }
+
+  target_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&ForwardingMessageFilter::ForwardToHandler, this, message));
+  return true;
+}
+
+ForwardingMessageFilter::~ForwardingMessageFilter() {
+}
+
+void ForwardingMessageFilter::ForwardToHandler(const Message& message) {
+  DCHECK(target_task_runner_->RunsTasksOnCurrentThread());
+  handler_.Run(message);
+}
+
+}  // namespace IPC