Update legacy Tuple-using code.

ppapi/proxy/resource_message_test_sink.cc

Index: ppapi/proxy/resource_message_test_sink.cc
diff --git a/ppapi/proxy/resource_message_test_sink.cc b/ppapi/proxy/resource_message_test_sink.cc
index 2c237b0670a10df4c89fd274d261ef2be37c4dea..2ce9f41a2d8436e71ee2c7156c32d92413bdbbf6 100644
--- a/ppapi/proxy/resource_message_test_sink.cc
+++ b/ppapi/proxy/resource_message_test_sink.cc
@@ -24,8 +24,8 @@ GetAllResourceMessagesMatching(const ResourceMessageTestSink& sink,
     if (msg->type() == WrapperMessage::ID) {
       typename WrapperMessage::Param params;
       WrapperMessage::Read(msg, &params);
-      Params cur_params = params.a;
-      IPC::Message cur_msg = params.b;
+      Params cur_params = get<0>(params);
+      IPC::Message cur_msg = get<1>(params);
       if (cur_msg.type() == id) {
         result.push_back(std::make_pair(cur_params, cur_msg));
       }
@@ -130,8 +130,8 @@ bool ResourceSyncCallHandler::OnMessageReceived(const IPC::Message& msg) {
   bool success = PpapiHostMsg_ResourceSyncCall::ReadSendParam(
       &msg, &send_params);
   DCHECK(success);
-  ResourceMessageCallParams call_params = send_params.a;
-  IPC::Message call_msg = send_params.b;
+  ResourceMessageCallParams call_params = get<0>(send_params);
+  IPC::Message call_msg = get<1>(send_params);
   if (call_msg.type() != incoming_type_)
     return false;
   IPC::Message* wrapper_reply_msg = IPC::SyncMessage::GenerateReply(&msg);