Standardize usage of virtual/override/final in mojo/

mojo/public/cpp/application/lib/weak_service_provider.h

Index: mojo/public/cpp/application/lib/weak_service_provider.h
diff --git a/mojo/public/cpp/application/lib/weak_service_provider.h b/mojo/public/cpp/application/lib/weak_service_provider.h
index 05ce939e87ff591c30fb46f29132a533c204b810..3d959d16baba6bfe1148ba6eff400ad70a0a7aab 100644
--- a/mojo/public/cpp/application/lib/weak_service_provider.h
+++ b/mojo/public/cpp/application/lib/weak_service_provider.h
@@ -20,14 +20,14 @@ class WeakServiceProvider : public ServiceProvider {
  public:
   WeakServiceProvider(ServiceProviderImpl* creator,
                       ServiceProvider* service_provider);
-  virtual ~WeakServiceProvider();
+  ~WeakServiceProvider() override;
 
   void Clear();
 
  private:
   // Overridden from ServiceProvider:
-  virtual void ConnectToService(const String& service_name,
-                                ScopedMessagePipeHandle client_handle) override;
+  void ConnectToService(const String& service_name,
+                        ScopedMessagePipeHandle client_handle) override;
 
   ServiceProviderImpl* creator_;
   ServiceProvider* service_provider_;