Add support for passing an arbitrary parameter to an IPC message handler. The motivation is for Web…

content/renderer/input/input_event_filter.cc

 // Copyright 2013 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.
 
 #include "content/renderer/input/input_event_filter.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/location.h"
@@ skipping 128 matching lines @@
         "InputEventFilter::ForwardToHandler::ForwardToMainListener",
         TRACE_EVENT_SCOPE_THREAD);
     main_loop_->PostTask(
         FROM_HERE,
         base::Bind(&InputEventFilter::ForwardToMainListener,
                    this, message));
     return;
   }
 
   int routing_id = message.routing_id();
-  ui::LatencyInfo latency_info;
-  const WebInputEvent* event = NULL;
-  bool is_keyboard_shortcut;
-  if (!InputMsg_HandleInputEvent::Read(
-          &message, &event, &latency_info, &is_keyboard_shortcut))
+  InputMsg_HandleInputEvent::Param params;
+  if (!InputMsg_HandleInputEvent::Read(&message, &params))
     return;
+  const WebInputEvent* event = params.a;
+  ui::LatencyInfo latency_info = params.b;
+  bool is_keyboard_shortcut = params.c;
   DCHECK(event);
 
   InputEventAckState ack = handler_.Run(routing_id, event, &latency_info);
 
   if (ack == INPUT_EVENT_ACK_STATE_NOT_CONSUMED) {
     TRACE_EVENT_INSTANT0(
         "input",
         "InputEventFilter::ForwardToHandler::ForwardToMainListener",
         TRACE_EVENT_SCOPE_THREAD);
     IPC::Message new_msg = InputMsg_HandleInputEvent(
@@ skipping 28 matching lines @@
 void InputEventFilter::SendMessageOnIOThread(const IPC::Message& message) {
   DCHECK(io_loop_->BelongsToCurrentThread());
 
   if (!sender_)
     return;  // Filter was removed.
 
   sender_->Send(new IPC::Message(message));
 }
 
 }  // namespace content