Standardize usage of virtual/override/final specifiers.

remoting/host/audio_capturer_linux.h

Index: remoting/host/audio_capturer_linux.h
diff --git a/remoting/host/audio_capturer_linux.h b/remoting/host/audio_capturer_linux.h
index 6f29a1b5e5545a6ad4ef8bc747385d1a97557296..a90d2a2b5df1330bdda5d7525ad6d247b11651cf 100644
--- a/remoting/host/audio_capturer_linux.h
+++ b/remoting/host/audio_capturer_linux.h
@@ -30,15 +30,15 @@ class AudioCapturerLinux : public AudioCapturer,
 
   explicit AudioCapturerLinux(
       scoped_refptr<AudioPipeReader> pipe_reader);
-  virtual ~AudioCapturerLinux();
+  ~AudioCapturerLinux() override;
 
   // AudioCapturer interface.
-  virtual bool Start(const PacketCapturedCallback& callback) override;
-  virtual void Stop() override;
-  virtual bool IsStarted() override;
+  bool Start(const PacketCapturedCallback& callback) override;
+  void Stop() override;
+  bool IsStarted() override;
 
   // AudioPipeReader::StreamObserver interface.
-  virtual void OnDataRead(scoped_refptr<base::RefCountedString> data) override;
+  void OnDataRead(scoped_refptr<base::RefCountedString> data) override;
 
  private:
   scoped_refptr<AudioPipeReader> pipe_reader_;