Fix virtual/override/final usage in Source/platform/.

Source/platform/plugins/PluginListBuilder.h

Index: Source/platform/plugins/PluginListBuilder.h
diff --git a/Source/platform/plugins/PluginListBuilder.h b/Source/platform/plugins/PluginListBuilder.h
index 0c6f9eac091e56b07517fbbabe6b8b2fca8f9ed0..9550cf7471335b273f096673fc6c7f11ae5912fd 100644
--- a/Source/platform/plugins/PluginListBuilder.h
+++ b/Source/platform/plugins/PluginListBuilder.h
@@ -42,9 +42,9 @@ public:
     PluginListBuilder(Vector<PluginInfo>* results) : m_results(results) { }
 
     // WebPluginListBuilder methods:
-    virtual void addPlugin(const WebString& name, const WebString& description, const WebString& fileName) override;
-    virtual void addMediaTypeToLastPlugin(const WebString& name, const WebString& description) override;
-    virtual void addFileExtensionToLastMediaType(const WebString& extension) override;
+    void addPlugin(const WebString& name, const WebString& description, const WebString& fileName) override;
+    void addMediaTypeToLastPlugin(const WebString& name, const WebString& description) override;
+    void addFileExtensionToLastMediaType(const WebString& extension) override;
 
 private:
     Vector<PluginInfo>* m_results;