Update legacy Tuple-using code.

content/browser/web_contents/web_contents_view_aura_browsertest.cc

 // 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.
 
 #include "content/browser/web_contents/web_contents_view_aura.h"
 
 #include "base/command_line.h"
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/test_timeouts.h"
@@ skipping 196 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);
-      blink::WebInputEvent::Type type = params.a.type;
-      InputEventAckState ack = params.a.state;
+      blink::WebInputEvent::Type type = get<0>(params).type;
+      InputEventAckState ack = get<0>(params).state;
       BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
           base::Bind(&InputEventMessageFilterWaitsForAcks::ReceivedEventAck,
                      this, type, ack));
     }
     return false;
   }
 
   base::Closure quit_;
   blink::WebInputEvent::Type type_;
   InputEventAckState state_;
@@ skipping 916 matching lines @@
     details = dispatcher->OnEventFromSource(&release);
     ASSERT_FALSE(details.dispatcher_destroyed);
     WaitAFrame();
 
     EXPECT_LT(0, tracker.num_overscroll_updates());
     EXPECT_FALSE(tracker.overscroll_completed());
   }
 }
 
 }  // namespace content