Add a test helper class for ExtensionRegistry.

extensions/browser/test_extension_registry_observer.h

Index: extensions/browser/test_extension_registry_observer.h
diff --git a/extensions/browser/test_extension_registry_observer.h b/extensions/browser/test_extension_registry_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..ce3beb07c1d2fea998f28099ee2d13d7b0ea754d
--- /dev/null
+++ b/extensions/browser/test_extension_registry_observer.h
@@ -0,0 +1,60 @@
+// Copyright 2014 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 EXTENSIONS_BROWSER_TEST_EXTENSION_REGISTRY_OBSERVER_H_
+#define EXTENSIONS_BROWSER_TEST_EXTENSION_REGISTRY_OBSERVER_H_
+
+#include "base/scoped_observer.h"
+#include "extensions/browser/extension_registry_observer.h"
+
+namespace extensions {
+class ExtensionRegistry;
+
+// A helper class that listen for ExtensionRegistry notifications.
+class TestExtensionRegistryObserver : public ExtensionRegistryObserver {
+ public:
+  explicit TestExtensionRegistryObserver(ExtensionRegistry* registry,
+                                         const std::string& extension_id);
+  virtual ~TestExtensionRegistryObserver();
+
+  void WaitForExtensionWillBeInstalled();
+  void WaitForExtensionUninstalled();
+  void WaitForExtensionLoaded();
+  void WaitForExtensionUnloaded();
+
+ private:
+  class Waiter;
+
+  // ExtensionRegistryObserver.
+  virtual void OnExtensionWillBeInstalled(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      bool is_update,
+      bool from_ephemeral,
+      const std::string& old_name) OVERRIDE;
+  virtual void OnExtensionUninstalled(content::BrowserContext* browser_context,
+                                      const Extension* extension) OVERRIDE;
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
+  scoped_ptr<Waiter> will_be_installed_waiter_;
+  scoped_ptr<Waiter> uninstalled_waiter_;
+  scoped_ptr<Waiter> loaded_waiter_;
+  scoped_ptr<Waiter> unloaded_waiter_;
+
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
+  std::string extension_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestExtensionRegistryObserver);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_TEST_EXTENSION_REGISTRY_OBSERVER_H_