Ensure that PP_Instance values are unique within a plugin process in addition...

ppapi/proxy/plugin_message_filter.cc

+// Copyright (c) 2011 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/plugin_message_filter.h"
+
+#include "ppapi/proxy/ppapi_messages.h"
+
+namespace pp {
+namespace proxy {
+
+PluginMessageFilter::PluginMessageFilter(
+    std::set<PP_Instance>* seen_instance_ids)
+    : seen_instance_ids_(seen_instance_ids),
+      channel_(NULL) {
+}
+
+PluginMessageFilter::~PluginMessageFilter() {
+}
+
+void PluginMessageFilter::OnFilterAdded(IPC::Channel* channel) {
+  channel_ = channel;
+}
+
+void PluginMessageFilter::OnFilterRemoved() {
+  channel_ = NULL;
+}
+
+bool PluginMessageFilter::OnMessageReceived(const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(PluginMessageFilter, message)
+    IPC_MESSAGE_HANDLER(PpapiMsg_ReserveInstanceId, OnMsgReserveInstanceId)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+bool PluginMessageFilter::Send(IPC::Message* msg) {
+  if (channel_)
+    return channel_->Send(msg);
+  delete msg;
+  return false;
+}
+
+void PluginMessageFilter::OnMsgReserveInstanceId(PP_Instance instance,
+                                                 bool* usable) {
+  // See the message definition for how this works.
+  if (seen_instance_ids_->find(instance) != seen_instance_ids_->end()) {
+    // Instance ID already seen, reject it.
+    *usable = false;
+    return;
+  }
+
+  // This instance ID is new so we can return that it's usable and mark it as
+  // used for future reference.
+  seen_instance_ids_->insert(instance);
+  *usable = true;
+}
+
+}  // namespace proxy
+}  // namespace pp