Fix chromium-style warnings in webrtc/sound/.

webrtc/sound/soundinputstreaminterface.h

Index: webrtc/sound/soundinputstreaminterface.h
diff --git a/webrtc/sound/soundinputstreaminterface.h b/webrtc/sound/soundinputstreaminterface.h
index 424ce8e9273fedc66217ab026c88992eaf117b41..2c934ba6799929c31381acdc07a25e39d0a5527f 100644
--- a/webrtc/sound/soundinputstreaminterface.h
+++ b/webrtc/sound/soundinputstreaminterface.h
@@ -21,7 +21,7 @@ namespace rtc {
 // for rtc::Worker.
 class SoundInputStreamInterface {
  public:
-  virtual ~SoundInputStreamInterface() {}
+  virtual ~SoundInputStreamInterface();
 
   // Starts the reading of samples on the current thread.
   virtual bool StartReading() = 0;
@@ -57,7 +57,7 @@ class SoundInputStreamInterface {
       SoundInputStreamInterface *> SignalSamplesRead;
 
  protected:
-  SoundInputStreamInterface() {}
+  SoundInputStreamInterface();
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(SoundInputStreamInterface);