Add a hang monitor for Pepper plugins

ppapi/proxy/host_dispatcher.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_HOST_DISPATCHER_H_
 #define PPAPI_PROXY_HOST_DISPATCHER_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/process.h"
+#include "ipc/ipc_channel_proxy.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/proxy/dispatcher.h"
 #include "ppapi/shared_impl/function_group_base.h"
 
 struct PPB_Proxy_Private;
 
 namespace ppapi {
 
 struct Preferences;
 
 namespace proxy {
 
 class PPAPI_PROXY_EXPORT HostDispatcher : public Dispatcher {
  public:
-  // Constructor for the renderer side.
+  // This interface receives notifications about sync messages being sent by
+  // the dispatcher to the plugin process. It is used to detect a hung plugin.
+  //
+  // Note that there can be nested sync messages, so the begin/end status
+  // actually represents a stack of blocking messages.
+  class SyncMessageStatusReceiver : public IPC::ChannelProxy::MessageFilter {
+   public:
+    virtual ~SyncMessageStatusReceiver() {}
+
+    // Notification that a sync message is about to be sent out.
+    virtual void BeginBlockOnSyncMessage() = 0;
+
+    // Notification that a sync message reply was received and the dispatcher
+    // is no longer blocked on a sync message.
+    virtual void EndBlockOnSyncMessage() = 0;
+  };
+
+  // Constructor for the renderer side. This will take a reference to the
+  // SyncMessageStatusReceiver.
   //
   // You must call InitHostWithChannel after the constructor.
   HostDispatcher(base::ProcessHandle host_process_handle,
                  PP_Module module,
-                 GetInterfaceFunc local_get_interface);
+                 GetInterfaceFunc local_get_interface,
+                 SyncMessageStatusReceiver* sync_status);
   ~HostDispatcher();
 
   // You must call this function before anything else. Returns true on success.
   // The delegate pointer must outlive this class, ownership is not
   // transferred.
   virtual bool InitHostWithChannel(Delegate* delegate,
                                    const IPC::ChannelHandle& channel_handle,
                                    bool is_client,
                                    const Preferences& preferences);
 
@@ skipping 39 matching lines @@
  protected:
   // Overridden from Dispatcher.
   virtual void OnInvalidMessageReceived();
 
  private:
   void OnHostMsgLogWithSource(PP_Instance instance,
                               int int_log_level,
                               const std::string& source,
                               const std::string& value);
 
+  scoped_refptr<SyncMessageStatusReceiver> sync_status_;
+
   PP_Module pp_module_;
 
   // Maps interface name to whether that interface is supported. If an interface
   // name is not in the map, that implies that we haven't queried for it yet.
   typedef base::hash_map<std::string, bool> PluginSupportedMap;
   PluginSupportedMap plugin_supported_;
 
   // Guaranteed non-NULL.
   const PPB_Proxy_Private* ppb_proxy_;
 
@@ skipping 21 matching lines @@
  private:
   HostDispatcher* dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedModuleReference);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_HOST_DISPATCHER_H_