Observe adding external extensions via windows registry.

extensions/browser/external_install_info.h

Index: extensions/browser/external_install_info.h
diff --git a/extensions/browser/external_install_info.h b/extensions/browser/external_install_info.h
new file mode 100644
index 0000000000000000000000000000000000000000..72a19e8b9c9c4a0ceae1887c4b9fcb6c305b60e0
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+++ b/extensions/browser/external_install_info.h
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+// Copyright 2016 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_EXTERNAL_INSTALL_INFO_H_
+#define EXTENSIONS_BROWSER_EXTERNAL_INSTALL_INFO_H_
+
+#include "base/files/file_path.h"
+#include "base/memory/scoped_vector.h"
+#include "extensions/common/manifest.h"
+
+class GURL;
+
+namespace base {
+class Version;
+}
+
+namespace extensions {
+
+// Holds information about an external extension install from an external
+// provider.
+struct ExternalInstallInfo {
+  ExternalInstallInfo(const std::string& extension_id,
+                      int creation_flags,
+                      bool mark_acknowledged);
+  virtual ~ExternalInstallInfo() {}
+
+  std::string extension_id;
+  int creation_flags;
+  bool mark_acknowledged;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ExternalInstallInfo);
+};
+
+struct ExternalInstallInfoFile : public ExternalInstallInfo {
+  ExternalInstallInfoFile(const std::string& extension_id,
+                          scoped_ptr<base::Version> version,
+                          const base::FilePath& path,
+                          Manifest::Location crx_location,
+                          int creation_flags,
+                          bool mark_acknowledged,
+                          bool install_immediately);
+  ~ExternalInstallInfoFile() override;
+
+  scoped_ptr<base::Version> version;
+  base::FilePath path;
+  Manifest::Location crx_location;
+  bool install_immediately;
+};
+
+struct ExternalInstallInfoUpdateUrl : public ExternalInstallInfo {
+  ExternalInstallInfoUpdateUrl(const std::string& extension_id,
+                               const std::string& install_parameter,
+                               scoped_ptr<GURL> update_url,
+                               Manifest::Location download_location,
+                               int creation_flags,
+                               bool mark_acknowledged);
+  ~ExternalInstallInfoUpdateUrl() override;
+
+  std::string install_parameter;
+  scoped_ptr<GURL> update_url;
+  Manifest::Location download_location;
+};
+
+}  // namespace extensions
+#endif  // EXTENSIONS_BROWSER_EXTERNAL_INSTALL_INFO_H_