ExtensionSystem cleanup part 2

extensions/browser/extension_system_provider.h

+// 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_EXTENSION_SYSTEM_PROVIDER_H_
+#define EXTENSIONS_BROWSER_EXTENSION_SYSTEM_PROVIDER_H_
+
+#include "components/browser_context_keyed_service/browser_context_keyed_service_factory.h"
+
+class BrowserContextDependencyManager;
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+class ExtensionSystem;
+
+// An ExtensionSystemProvider maps a BrowserContext to its ExtensionSystem.
+// Different applications may use this to provide differing implementations
+// of ExtensionSystem.
+// TODO(yoz): Rename to ExtensionSystemFactory.
+class ExtensionSystemProvider : public BrowserContextKeyedServiceFactory {
+ public:
+  ExtensionSystemProvider(const char* name,
+                          BrowserContextDependencyManager* manager);
+  virtual ~ExtensionSystemProvider();
+
+  virtual ExtensionSystem* GetForBrowserContext(
+      content::BrowserContext* context) = 0;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_EXTENSION_SYSTEM_PROVIDER_H_