Move small c/b/extensions classes into extensions namespace no.1

chrome/browser/extensions/extension_activity_log.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_ACTIVITY_LOG_H_
-#define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACTIVITY_LOG_H_
-
-#include <map>
-#include <string>
-
-#include "base/memory/singleton.h"
-#include "base/observer_list_threadsafe.h"
-#include "base/synchronization/lock.h"
-
-namespace extensions {
-class Extension;
-}
-
-// A utility for tracing interesting activity for each extension.
-class ExtensionActivityLog {
- public:
-  enum Activity {
-    ACTIVITY_EXTENSION_API_CALL,  // Extension API invocation is called.
-    ACTIVITY_EXTENSION_API_BLOCK  // Extension API invocation is blocked.
-  };
-
-  // Observers can listen for activity events.
-  class Observer {
-   public:
-    virtual void OnExtensionActivity(const extensions::Extension* extension,
-                                     Activity activity,
-                                     const std::string& msg) = 0;
-  };
-
-  ~ExtensionActivityLog();
-  static ExtensionActivityLog* GetInstance();
-
-  // Add/remove observer.
-  void AddObserver(const extensions::Extension* extension, Observer* observer);
-  void RemoveObserver(const extensions::Extension* extension,
-                      Observer* observer);
-
-  // Check for the existence observer list by extension_id.
-  bool HasObservers(const extensions::Extension* extension) const;
-
-  // Log |activity| for |extension|.
-  void Log(const extensions::Extension* extension,
-           Activity activity,
-           const std::string& msg) const;
-
- private:
-  ExtensionActivityLog();
-  friend struct DefaultSingletonTraits<ExtensionActivityLog>;
-
-  static const char* ActivityToString(Activity activity);
-
-  // A lock used to synchronize access to member variables.
-  mutable base::Lock lock_;
-
-  // Whether to log activity to stdout. This is set by checking the
-  // enable-extension-activity-logging switch.
-  bool log_activity_to_stdout_;
-
-  typedef ObserverListThreadSafe<Observer> ObserverList;
-  typedef std::map<const extensions::Extension*, scoped_refptr<ObserverList> >
-      ObserverMap;
-  // A map of extensions to activity observers for that extension.
-  ObserverMap observers_;
-
-  DISALLOW_COPY_AND_ASSIGN(ExtensionActivityLog);
-};
-
-#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACTIVITY_LOG_H_