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

ppapi/host/ppapi_host.cc

Index: ppapi/host/ppapi_host.cc
diff --git a/ppapi/host/ppapi_host.cc b/ppapi/host/ppapi_host.cc
index cbb989b5dc0c1fd4ba2822d90451577f11e98075..fcd415265d065b60d2cf3f62f3d8d2a8dbab51b2 100644
--- a/ppapi/host/ppapi_host.cc
+++ b/ppapi/host/ppapi_host.cc
@@ -12,11 +12,14 @@
 #include "ppapi/host/resource_host.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/resource_message_params.h"
+#include "ppapi/proxy/serialized_handle.h"
 #include "ppapi/shared_impl/host_resource.h"
 
 namespace ppapi {
 namespace host {
 
+using ppapi::proxy::SerializedHandle;
+
 namespace {
 
 // Put a cap on the maximum number of resources so we don't explode if the
@@ -99,11 +102,19 @@ void PpapiHost::SendReply(const ReplyMessageContext& context,
 
 void PpapiHost::SendUnsolicitedReply(PP_Resource resource,
                                      const IPC::Message& msg) {
-  TRACE_EVENT2("ppapi proxy", "PpapiHost::SendUnsolicitedReply",
+  SendUnsolicitedReplyWithHandle(resource, msg, SerializedHandle());
+}
+
+void PpapiHost::SendUnsolicitedReplyWithHandle(PP_Resource resource,
+                                               const IPC::Message& msg,
+                                               const SerializedHandle& handle) {
+  TRACE_EVENT2("ppapi proxy", "PpapiHost::SendUnsolicitedReplyWithHandle",
                "Class", IPC_MESSAGE_ID_CLASS(msg.type()),
                "Line", IPC_MESSAGE_ID_LINE(msg.type()));
   DCHECK(resource);  // If this fails, host is probably pending.
   proxy::ResourceMessageReplyParams params(resource, 0);
+  if (handle.IsHandleValid())
+    params.AppendHandle(handle);
   Send(new PpapiPluginMsg_ResourceReply(params, msg));
 }