PPAPI: Support sending browser-hosted resources synchronously

ppapi/proxy/ppapi_messages.h

Index: ppapi/proxy/ppapi_messages.h
diff --git a/ppapi/proxy/ppapi_messages.h b/ppapi/proxy/ppapi_messages.h
index 135786cd220cd14ac3d8118aaaa6d308ee5b3694..4eb3b91382dc0f9eefbb332a2dff683eb8785df7 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -429,6 +429,11 @@ IPC_STRUCT_TRAITS_BEGIN(ppapi::PpapiNaClPluginArgs)
   IPC_STRUCT_TRAITS_MEMBER(switch_values)
 IPC_STRUCT_TRAITS_END()
 
+IPC_STRUCT_TRAITS_BEGIN(ppapi::proxy::CompletedBrowserResourceHosts)
+  IPC_STRUCT_TRAITS_MEMBER(sequence_id)
+  IPC_STRUCT_TRAITS_MEMBER(host_ids)
+IPC_STRUCT_TRAITS_END()
+
 #if !defined(OS_NACL) && !defined(NACL_WIN64)
 
 IPC_STRUCT_TRAITS_BEGIN(ppapi::proxy::PPPDecryptor_Buffer)
@@ -1336,10 +1341,29 @@ IPC_MESSAGE_CONTROL5(
 // in the request and the IDs of the pending ResourceHosts which were created in
 // the browser. These IDs are only useful for the plugin which can attach to the
 // ResourceHosts in the browser.
-IPC_MESSAGE_ROUTED2(
+IPC_MESSAGE_ROUTED1(
     PpapiHostMsg_CreateResourceHostsFromHostReply,
-    int32_t /* sequence */,
-    std::vector<int> /* pending_host_ids */)
+    ppapi::proxy::CompletedBrowserResourceHosts /* completed_hosts */)
+
+// The renderer sends this back to the browser to acknowledge receipt of the
+// pending_host_ids. The browser has to keep track of the pending_host_ids until
+// it receives this Ack, in case a sync message comes along needing the
+// pending_host_ids immediately, possibly before the above Reply has been
+// received.
+IPC_MESSAGE_CONTROL3(
+    PpapiHostMsg_CreateResourceHostsFromHostReplyAck,
+    int /* child_process_id */,
+    PP_Instance /* instance */,
+    int /* sequence_num */)
+
+// The renderer can send this to the browser to retrieve all pending hosts
+// synchronously.
+IPC_SYNC_MESSAGE_CONTROL3_1(
+    PpapiHostMsg_GetAllPendingResourceHosts,
+    int /* routing_id */,
+    int /* child_process_id */,
+    PP_Instance /* instance */,
+    std::vector<ppapi::proxy::CompletedBrowserResourceHosts>)
 
 //-----------------------------------------------------------------------------
 // Messages for resources using call/reply above.