Create thread-safe RendererExtensionRegistry from ExtensionSet

extensions/renderer/renderer_extension_registry.h

Index: extensions/renderer/renderer_extension_registry.h
diff --git a/extensions/renderer/renderer_extension_registry.h b/extensions/renderer/renderer_extension_registry.h
new file mode 100644
index 0000000000000000000000000000000000000000..6a887a16d4f92e3be4c6ad98ed90ce6ea63ce206
--- /dev/null
+++ b/extensions/renderer/renderer_extension_registry.h
@@ -0,0 +1,59 @@
+// Copyright 2015 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_RENDERER_RENDERER_EXTENSION_REGISTRY_H_
+#define EXTENSIONS_RENDERER_RENDERER_EXTENSION_REGISTRY_H_
+
+#include <string>
+
+#include "base/synchronization/lock.h"
+#include "extensions/common/extension_set.h"
+
+class GURL;
+
+namespace extensions {
+
+// Thread safe container for all loaded extensions in this process,
+// essentially the renderer counterpart to ExtensionRegistry.
+class RendererExtensionRegistry {
+ public:
+  RendererExtensionRegistry();
+  ~RendererExtensionRegistry();
+
+  static RendererExtensionRegistry* Get();
+
+  // Returns the ExtensionSet that underlies this RenderExtensionRegistry.
+  //
+  // This is not thread-safe and must only be called on the RenderThread, but
+  // even so, it's not thread safe because other threads may decide to
+  // modify this. Don't persist a reference to this.
+  //
+  // TODO(annekao): remove or make thread-safe and callback-based.
+  const ExtensionSet* GetMainThreadExtensionSet() const;
+
+  size_t size() const;
+  bool is_empty() const;
+
+  // Forwards to the ExtensionSet methods by the same name.
+  bool Contains(const std::string& id) const;
+  bool Insert(const scoped_refptr<const Extension>& extension);
+  bool Remove(const std::string& id);
+  std::string GetExtensionOrAppIDByURL(const GURL& url) const;
+  const Extension* GetExtensionOrAppByURL(const GURL& url) const;
+  const Extension* GetHostedAppByURL(const GURL& url) const;
+  const Extension* GetByID(const std::string& id) const;
+  ExtensionIdSet GetIDs() const;
+  bool ExtensionBindingsAllowed(const GURL& url) const;
+
+ private:
+  ExtensionSet extensions_;
+
+  mutable base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(RendererExtensionRegistry);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_RENDERER_EXTENSION_REGISTRY_H_