[chromium-reviews] Add getLanguage function to tabs extension

chrome/browser/extensions/extension_function.h

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_H_
 
 #include <string>
 
 #include "base/values.h"
@@ skipping 75 matching lines @@
 // TODO(aa) Remove this extra level of inheritance once the browser stops
 // parsing JSON (and instead uses custom serialization of Value objects).
 class AsyncExtensionFunction : public ExtensionFunction {
  public:
   AsyncExtensionFunction() : args_(NULL), bad_message_(false) {}
   virtual ~AsyncExtensionFunction() {}
 
   virtual void SetArgs(const std::string& args);
   virtual const std::string GetResult();
   virtual const std::string GetError() { return error_; }
-  virtual void Run() = 0;
+  virtual void Run() {
+    if (!RunImpl())
+      SendResponse(false);
+  }
+
+  // Derived classes should implement this method to do their work and return
+  // success/failure.
+  virtual bool RunImpl() = 0;
 
  protected:
   void SendResponse(bool success);
 
   // Note: After Run() returns, dispatcher() can be NULL.  Since these getters
   // rely on dispatcher(), make sure it is valid before using them.
   std::string extension_id();
   Profile* profile();
 
   // The arguments to the API. Only non-null if argument were specified.
   Value* args_;
 
   // The result of the API. This should be populated by the derived class before
-  // Run() returns.
+  // SendResponse() is called.
   scoped_ptr<Value> result_;
 
   // Any detailed error from the API. This should be populated by the derived
   // class before Run() returns.
   std::string error_;
 
   // Any class that gets a malformed message should set this to true before
   // returning.  The calling renderer process will be killed.
   bool bad_message_;
 
@@ skipping 18 matching lines @@
 
   virtual void Run() {
     SendResponse(RunImpl());
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncExtensionFunction);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_H_