Standardize usage of virtual/override/final in content/

content/gpu/in_process_gpu_thread.h

Index: content/gpu/in_process_gpu_thread.h
diff --git a/content/gpu/in_process_gpu_thread.h b/content/gpu/in_process_gpu_thread.h
index 06d4a463a7f0d908c197c56c3654b7edee5f2c73..e8e0140dc2809ff7ca23003176e3b2ccc632b1fc 100644
--- a/content/gpu/in_process_gpu_thread.h
+++ b/content/gpu/in_process_gpu_thread.h
@@ -17,11 +17,11 @@ class GpuProcess;
 class InProcessGpuThread : public base::Thread {
  public:
   explicit InProcessGpuThread(const std::string& channel_id);
-  virtual ~InProcessGpuThread();
+  ~InProcessGpuThread() override;
 
  protected:
-  virtual void Init() override;
-  virtual void CleanUp() override;
+  void Init() override;
+  void CleanUp() override;
 
  private:
   std::string channel_id_;