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

content/browser/renderer_host/input/touch_input_browsertest.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 "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/run_loop.h"
 #include "content/browser/gpu/compositor_util.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
@@ skipping 93 matching lines @@
     if (type_ == type) {
       state_ = state;
       quit_.Run();
     }
   }
 
   // BrowserMessageFilter:
   virtual bool OnMessageReceived(const IPC::Message& message,
                                  bool* message_was_ok) OVERRIDE {
     if (message.type() == InputHostMsg_HandleInputEvent_ACK::ID) {
-      ui::LatencyInfo latency;
-      WebInputEvent::Type type = WebInputEvent::Undefined;
-      InputEventAckState ack = INPUT_EVENT_ACK_STATE_UNKNOWN;
-      InputHostMsg_HandleInputEvent_ACK::Read(&message, &type, &ack, &latency);
+      InputHostMsg_HandleInputEvent_ACK::Param params;
+      InputHostMsg_HandleInputEvent_ACK::Read(&message, &params);
+      WebInputEvent::Type type = params.a;
+      InputEventAckState ack = params.b;
       BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
           base::Bind(&InputEventMessageFilter::ReceivedEventAck,
                      this, type, ack));
     }
     return false;
   }
 
   base::Closure quit_;
   WebInputEvent::Type type_;
   InputEventAckState state_;
@@ skipping 129 matching lines @@
     EXPECT_EQ(INPUT_EVENT_ACK_STATE_NOT_CONSUMED, filter()->last_ack_state());
   }
 
   touch.PressPoint(25, 125);
   GetWidgetHost()->ForwardTouchEventWithLatencyInfo(touch, ui::LatencyInfo());
   filter()->WaitForAck(WebInputEvent::TouchStart);
   EXPECT_EQ(INPUT_EVENT_ACK_STATE_CONSUMED, filter()->last_ack_state());
 }
 
 }  // namespace content