Allow app_shell to run past extension manifest parsing

extensions/common/common_manifest_handlers.h

Index: extensions/common/common_manifest_handlers.h
diff --git a/extensions/common/common_manifest_handlers.h b/extensions/common/common_manifest_handlers.h
new file mode 100644
index 0000000000000000000000000000000000000000..ebeb1b59f10482034edd7125139cf47ab7e18134
--- /dev/null
+++ b/extensions/common/common_manifest_handlers.h
@@ -0,0 +1,17 @@
+// Copyright 2013 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_COMMON_COMMON_MANIFEST_HANDLERS_H_
+#define EXTENSIONS_COMMON_COMMON_MANIFEST_HANDLERS_H_
+
+namespace extensions {
+
+// Registers manifest handlers used by all embedders of the extensions system.
+// Should be called once in each process. Embedders may also wish to register
+// their own set of manifest handlers, such as chrome_manifest_handlers.cc.
+void RegisterCommonManifestHandlers();
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_COMMON_COMMON_MANIFEST_HANDLERS_H_