Fix chromium-style warnings in webrtc/sound/.

webrtc/sound/soundsystemproxy.h

Index: webrtc/sound/soundsystemproxy.h
diff --git a/webrtc/sound/soundsystemproxy.h b/webrtc/sound/soundsystemproxy.h
index d13cf15b7422c3b3d6e7798e88845c15420f9fad..19696b1fef42812de7958f9e5988fc24c91629f6 100644
--- a/webrtc/sound/soundsystemproxy.h
+++ b/webrtc/sound/soundsystemproxy.h
@@ -25,18 +25,18 @@ class SoundSystemProxy : public SoundSystemInterface {
 
   // Each of these methods simply defers to wrapped_ if non-NULL, else fails.
 
-  virtual bool EnumeratePlaybackDevices(SoundDeviceLocatorList *devices);
-  virtual bool EnumerateCaptureDevices(SoundDeviceLocatorList *devices);
+  bool EnumeratePlaybackDevices(SoundDeviceLocatorList *devices) override;
+  bool EnumerateCaptureDevices(SoundDeviceLocatorList *devices) override;
 
-  virtual bool GetDefaultPlaybackDevice(SoundDeviceLocator **device);
-  virtual bool GetDefaultCaptureDevice(SoundDeviceLocator **device);
+  bool GetDefaultPlaybackDevice(SoundDeviceLocator **device) override;
+  bool GetDefaultCaptureDevice(SoundDeviceLocator **device) override;
 
-  virtual SoundOutputStreamInterface *OpenPlaybackDevice(
+  SoundOutputStreamInterface *OpenPlaybackDevice(
       const SoundDeviceLocator *device,
-      const OpenParams &params);
-  virtual SoundInputStreamInterface *OpenCaptureDevice(
+      const OpenParams &params) override;
+  SoundInputStreamInterface *OpenCaptureDevice(
       const SoundDeviceLocator *device,
-      const OpenParams &params);
+      const OpenParams &params) override;
 
  protected:
   SoundSystemInterface *wrapped_;