Update legacy Tuple-using code.

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 94 matching lines @@
       state_ = state;
       quit_.Run();
     }
   }
 
   // BrowserMessageFilter:
   bool OnMessageReceived(const IPC::Message& message) override {
     if (message.type() == InputHostMsg_HandleInputEvent_ACK::ID) {
       InputHostMsg_HandleInputEvent_ACK::Param params;
       InputHostMsg_HandleInputEvent_ACK::Read(&message, &params);
-      WebInputEvent::Type type = params.a.type;
-      InputEventAckState ack = params.a.state;
+      WebInputEvent::Type type = get<0>(params).type;
+      InputEventAckState ack = get<0>(params).state;
       BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
           base::Bind(&InputEventMessageFilter::ReceivedEventAck,
                      this, type, ack));
     }
     return false;
   }
 
   base::Closure quit_;
   WebInputEvent::Type type_;
   InputEventAckState state_;
@@ skipping 117 matching lines @@
   EXPECT_EQ(INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS,
             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