Extract ExtensionFunctionRegistry from ExtensionFunctionDispatcher.

chrome/browser/extensions/extension_function_registry.h

+// Copyright (c) 2012 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_REGISTRY_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_REGISTRY_H_
+#pragma once
+
+#include <map>
+#include <string>
+#include <vector>
+
+class ExtensionFunction;
+
+// A factory function for creating new ExtensionFunction instances.
+typedef ExtensionFunction* (*ExtensionFunctionFactory)();
+
+// Template for defining ExtensionFunctionFactory.
+template<class T>
+ExtensionFunction* NewExtensionFunction() {
+  return new T();
+}
+
+// Contains a list of all known extension functions and allows clients to
+// create instances of them.
+class ExtensionFunctionRegistry {
+ public:
+  static ExtensionFunctionRegistry* GetInstance();
+  explicit ExtensionFunctionRegistry();
+  virtual ~ExtensionFunctionRegistry();
+
+  // Resets all functions to their default values.
+  void ResetFunctions();
+
+  // Adds all function names to 'names'.
+  void GetAllNames(std::vector<std::string>* names);
+
+  // Allows overriding of specific functions (e.g. for testing).  Functions
+  // must be previously registered.  Returns true if successful.
+  bool OverrideFunction(const std::string& name,
+                        ExtensionFunctionFactory factory);
+
+  // Factory method for the ExtensionFunction registered as 'name'.
+  ExtensionFunction* NewFunction(const std::string& name);
+
+  template<class T>
+  void RegisterFunction() {
+    factories_[T::function_name()] = &NewExtensionFunction<T>;
+  }
+
+ private:
+  typedef std::map<std::string, ExtensionFunctionFactory> FactoryMap;
+  FactoryMap factories_;
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_REGISTRY_H_