Add a hang monitor for Pepper plugins

content/browser/ppapi_plugin_process_host.h

Index: content/browser/ppapi_plugin_process_host.h
diff --git a/content/browser/ppapi_plugin_process_host.h b/content/browser/ppapi_plugin_process_host.h
index 02e1f835349718da4bd0f53f991fdcb003394e8b..3d7436ecb538a33b225c01fe08e86374da62e5e7 100644
--- a/content/browser/ppapi_plugin_process_host.h
+++ b/content/browser/ppapi_plugin_process_host.h
@@ -42,10 +42,12 @@ class PpapiPluginProcessHost : public content::BrowserChildProcessHostDelegate,
     // Called when the channel is asynchronously opened to the plugin or on
     // error. On error, the parameters should be:
     //   base::kNullProcessHandle
-    //   IPC::ChannelHandle()
+    //   IPC::ChannelHandle(),
+    //   0
     virtual void OnPpapiChannelOpened(
         base::ProcessHandle plugin_process_handle,
-        const IPC::ChannelHandle& channel_handle) = 0;
+        const IPC::ChannelHandle& channel_handle,
+        int plugin_child_id) = 0;
   };
 
   class PluginClient : public Client {
@@ -120,9 +122,6 @@ class PpapiPluginProcessHost : public content::BrowserChildProcessHostDelegate,
 
   const bool is_broker_;
 
-  // The unique id created for the process.
-  int process_id_;
-
   scoped_ptr<BrowserChildProcessHostImpl> process_;
 
   DISALLOW_COPY_AND_ASSIGN(PpapiPluginProcessHost);