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

ppapi/proxy/plugin_message_filter.h

+// 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.
+
+#ifndef PPAPI_PROXY_PLUGIN_MESSAGE_FILTER_H_
+#define PPAPI_PROXY_PLUGIN_MESSAGE_FILTER_H_
+
+#include <set>
+
+#include "ipc/ipc_channel_proxy.h"
+#include "ipc/ipc_message.h"
+#include "ppapi/c/pp_instance.h"
+
+namespace pp {
+namespace proxy {
+
+// Listens for messages on the I/O thread of the plugin and handles some of
+// them to avoid needing to block on the plugin.
+//
+// There is one instance of this class for each renderer channel (same as for
+// the PluginDispatchers).
+class PluginMessageFilter : public IPC::ChannelProxy::MessageFilter,
+                            public IPC::Message::Sender {
+ public:
+  // The input is a pointer to a set that will be used to uniquify PP_Instances
+  // across all renderer channels. The same pointer should be passed to each
+  // MessageFilter to ensure uniqueness, and the value should outlive this
+  // class.
+  PluginMessageFilter(std::set<PP_Instance>* seen_instance_ids);
+  virtual ~PluginMessageFilter();
+
+  // MessageFilter implementation.
+  virtual void OnFilterAdded(IPC::Channel* channel);
+  virtual void OnFilterRemoved();
+  virtual bool OnMessageReceived(const IPC::Message& message);
+
+  // Message::Sender implementation.
+  virtual bool Send(IPC::Message* msg);
+
+ private:
+  void OnMsgReserveInstanceId(PP_Instance instance, bool* usable);
+
+  // All instance IDs every queried by any renderer on this plugin. This is
+  // used to make sure that new instance IDs are unique. This is a non-owning
+  // pointer, it will be managed by the later that creates this class.
+  std::set<PP_Instance>* seen_instance_ids_;
+
+  // The IPC channel to the renderer. May be NULL if we're not currently
+  // attached as a filter.
+  IPC::Channel* channel_;
+};
+
+}  // namespace proxy
+}  // namespace pp
+
+#endif  // PPAPI_PROXY_PLUGIN_MESSAGE_FILTER_H_