[PPAPI] Implement an IOStreamResource for data transmission between plugin and renderer.

ppapi/host/ppapi_host.h

Index: ppapi/host/ppapi_host.h
diff --git a/ppapi/host/ppapi_host.h b/ppapi/host/ppapi_host.h
index 5a7c5c45c2a495c4e237030442741c6f67e67382..fb72e1a40bda90d7ffb8bf87f1001ddaca33f372 100644
--- a/ppapi/host/ppapi_host.h
+++ b/ppapi/host/ppapi_host.h
@@ -24,6 +24,7 @@ namespace ppapi {
 namespace proxy {
 class ResourceMessageCallParams;
 class ResourceMessageReplyParams;
+class SerializedHandle;
 }
 
 namespace host {
@@ -61,6 +62,12 @@ class PPAPI_HOST_EXPORT PpapiHost : public IPC::Sender, public IPC::Listener {
   // Sends the given unsolicited reply message to the plugin.
   void SendUnsolicitedReply(PP_Resource resource, const IPC::Message& msg);
 
+  // Similar to SendUnsolicitedReply, but it support sending a file handle.
+  void SendUnsolicitedReplyWithHandle(
+      PP_Resource resource,
+      const IPC::Message& msg,
+      const ppapi::proxy::SerializedHandle& handle);
+
   // Create a ResourceHost with the given |nested_msg|.
   scoped_ptr<ResourceHost> CreateResourceHost(
       const proxy::ResourceMessageCallParams& params,