use variadic macros/templates in IPC message implementation

content/renderer/input/input_event_filter.cc

Index: content/renderer/input/input_event_filter.cc
diff --git a/content/renderer/input/input_event_filter.cc b/content/renderer/input/input_event_filter.cc
index c85586272fd1a36742db5e8fda60b93802b6c9fe..927a402b0eecd2c7ca79b4e47e8fdcde453325c6 100644
--- a/content/renderer/input/input_event_filter.cc
+++ b/content/renderer/input/input_event_filter.cc
@@ -26,8 +26,9 @@ using blink::WebInputEvent;
 
 #include "ipc/ipc_message_null_macros.h"
 #undef IPC_MESSAGE_DECL
-#define IPC_MESSAGE_DECL(kind, type, name, in, out, ilist, olist) \
-  case name::ID: return #name;
+#define IPC_MESSAGE_DECL(name, ...) \

[vmpstr, 2016/02/04 23:43:27]

Where is this used? I tried to see if you updated the callsites to use the first
parameter as name instead of third, but I can't really find where this is used
:)

[mdempsky, 2016/02/05 00:32:32]

It's used indirectly via the #include "content/common/input_messages.h" below. 
That file declares a bunch of messages, which will then be instantiated using
this IPC_MESSAGE_DECL macro definition instead, which is how they implement
GetInputMessageTypeName's switch statement.

+  case name::ID:                    \
+    return #name;
 
 const char* GetInputMessageTypeName(const IPC::Message& message) {
   switch (message.type()) {