Update legacy Tuple-using code.

ppapi/host/dispatch_host_message.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file provides infrastructure for dispatching host resource call
 // messages. Normal IPC message handlers can't take extra parameters or
 // return values. We want to take a HostMessageContext as a parameter and
 // also return the int32_t return value to the caller.
 
 #ifndef PPAPI_HOST_DISPATCH_HOST_MESSAGE_H_
 #define PPAPI_HOST_DISPATCH_HOST_MESSAGE_H_
 
 #include "base/profiler/scoped_profile.h"
 #include "ipc/ipc_message_macros.h"
 #include "ppapi/c/pp_errors.h"
 
 namespace ppapi {
 namespace host {
 
 struct HostMessageContext;
 
 template <class ObjT, class Method>
 inline int32_t DispatchResourceCall(ObjT* obj, Method method,
                                     HostMessageContext* context,
-                                    Tuple0& arg) {
+                                    Tuple<>& arg) {

[Nico, 2014/12/22 17:03:12]

can possibly be a variadic template

   return (obj->*method)(context);
 }
 
 template <class ObjT, class Method, class A>
 inline int32_t DispatchResourceCall(ObjT* obj, Method method,
                                     HostMessageContext* context,
-                                    Tuple1<A>& arg) {
-  return (obj->*method)(context, arg.a);
+                                    Tuple<A>& arg) {
+  return (obj->*method)(context, get<0>(arg));
 }
 
 template<class ObjT, class Method, class A, class B>
 inline int32_t DispatchResourceCall(ObjT* obj, Method method,
                                     HostMessageContext* context,
-                                    Tuple2<A, B>& arg) {
-  return (obj->*method)(context, arg.a, arg.b);
+                                    Tuple<A, B>& arg) {
+  return (obj->*method)(context, get<0>(arg), get<1>(arg));
 }
 
 template<class ObjT, class Method, class A, class B, class C>
 inline int32_t DispatchResourceCall(ObjT* obj, Method method,
                                     HostMessageContext* context,
-                                    Tuple3<A, B, C>& arg) {
-  return (obj->*method)(context, arg.a, arg.b, arg.c);
+                                    Tuple<A, B, C>& arg) {
+  return (obj->*method)(context, get<0>(arg), get<1>(arg), get<2>(arg));
 }
 
 template<class ObjT, class Method, class A, class B, class C, class D>
 inline int32_t DispatchResourceCall(ObjT* obj, Method method,
                                     HostMessageContext* context,
-                                    Tuple4<A, B, C, D>& arg) {
-  return (obj->*method)(context, arg.a, arg.b, arg.c, arg.d);
+                                    Tuple<A, B, C, D>& arg) {
+  return (obj->*method)(context, get<0>(arg), get<1>(arg), get<2>(arg),
+                        get<3>(arg));
 }
 
 template<class ObjT, class Method, class A, class B, class C, class D, class E>
 inline int32_t DispatchResourceCall(ObjT* obj, Method method,
                                     HostMessageContext* context,
-                                    Tuple5<A, B, C, D, E>& arg) {
-  return (obj->*method)(context, arg.a, arg.b, arg.c, arg.d, arg.e);
+                                    Tuple<A, B, C, D, E>& arg) {
+  return (obj->*method)(context, get<0>(arg), get<1>(arg), get<2>(arg),
+                        get<3>(arg), get<4>(arg));
 }
 
 // Note that this only works for message with 1 or more parameters. For
 // 0-parameter messages you need to use the _0 version below (since there are
 // no params in the message).
 #define PPAPI_DISPATCH_HOST_RESOURCE_CALL(msg_class, member_func) \
     case msg_class::ID: { \
       TRACK_RUN_IN_THIS_SCOPED_REGION(member_func); \
       msg_class::Schema::Param p; \
       if (msg_class::Read(&ipc_message__, &p)) { \
         return ppapi::host::DispatchResourceCall( \
             this, \
             &_IpcMessageHandlerClass::member_func, \
             context, p); \
       } \
       return PP_ERROR_FAILED; \
     }
 
 #define PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(msg_class, member_func) \
   case msg_class::ID: { \
     TRACK_RUN_IN_THIS_SCOPED_REGION(member_func); \
     return member_func(context); \
   }
 
 }  // namespace host
 }  // namespace ppapi
 
 #endif  // PPAPI_HOST_DISPATCH_HOST_MESSAGE_H_