Add the "virtual" keyword on method overrides that are missing it.

chrome/worker/nativewebworker_impl.h

Index: chrome/worker/nativewebworker_impl.h
diff --git a/chrome/worker/nativewebworker_impl.h b/chrome/worker/nativewebworker_impl.h
index c2be7fc6f0f68c9880dcf600443970387cd8da13..528c31d1181d674d5f4f936c4592e544655a6912 100644
--- a/chrome/worker/nativewebworker_impl.h
+++ b/chrome/worker/nativewebworker_impl.h
@@ -24,15 +24,15 @@ class NativeWebWorkerImpl : public WebKit::WebWorker {
   static WebWorker* create(WebKit::WebWorkerClient* client);
 
   // WebWorker implementation.
-  void startWorkerContext(const WebKit::WebURL& script_url,
-                          const WebKit::WebString& user_agent,
-                          const WebKit::WebString& source_code);
-  void terminateWorkerContext();
-  void postMessageToWorkerContext(
+  virtual void startWorkerContext(const WebKit::WebURL& script_url,
+                                  const WebKit::WebString& user_agent,
+                                  const WebKit::WebString& source_code);
+  virtual void terminateWorkerContext();
+  virtual void postMessageToWorkerContext(
       const WebKit::WebString& message,
       const WebKit::WebMessagePortChannelArray& channels);
-  void workerObjectDestroyed();
-  void clientDestroyed();
+  virtual void workerObjectDestroyed();
+  virtual void clientDestroyed();
 
  private:
   WebKit::WebWorkerClient* client_;