test_runner: Migrate MockWebAudioDevice to our Chromium C++ style.

content/shell/renderer/test_runner/mock_web_audio_device.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/shell/renderer/test_runner/MockWebAudioDevice.h"
+#include "content/shell/renderer/test_runner/mock_web_audio_device.h"
 
 namespace content {
 
-MockWebAudioDevice::MockWebAudioDevice(double sampleRate)
-    : m_sampleRate(sampleRate)
-{
-}
+MockWebAudioDevice::MockWebAudioDevice(double sample_rate)
+    : sample_rate_(sample_rate) {}
 
-MockWebAudioDevice::~MockWebAudioDevice()
-{
-}
+MockWebAudioDevice::~MockWebAudioDevice() {}
 
-void MockWebAudioDevice::start()
-{
-}
+void MockWebAudioDevice::start() {}
 
-void MockWebAudioDevice::stop()
-{
-}
+void MockWebAudioDevice::stop() {}
 
-double MockWebAudioDevice::sampleRate()
-{
-    return m_sampleRate;
+double MockWebAudioDevice::sampleRate() {
+  return sample_rate_;
 }
 
 }  // namespace content