Add extensions code to use common updater in components/update_client/

extensions/browser/updater/update_install_shim.h

Index: extensions/browser/updater/update_install_shim.h
diff --git a/extensions/browser/updater/update_install_shim.h b/extensions/browser/updater/update_install_shim.h
new file mode 100644
index 0000000000000000000000000000000000000000..586e94e2167a60a30f7bd80d8d5321d62ba7f7cf
--- /dev/null
+++ b/extensions/browser/updater/update_install_shim.h
@@ -0,0 +1,76 @@
+// 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_BROWSER_UPDATER_UPDATE_INSTALL_SHIM_H_
+#define EXTENSIONS_BROWSER_UPDATER_UPDATE_INSTALL_SHIM_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "components/update_client/update_client.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace extensions {
+
+// A callback to implement the install of a new version of the extension.
+// Takes ownership of the directory at |temp_dir|.
+using UpdateInstallShimCallback =
+    base::Callback<void(const std::string& extension_id,
+                        const base::FilePath& temp_dir)>;
+
+// This class is used as a shim between the components::update_client and
+// extensions code, to help the generic update_client code prepare and then
+// install an updated version of an extension. Because the update_client code
+// doesn't have the notion of extension ids, we use instances of this class to
+// map an install request back to the original update check for a given
+// extension.
+class UpdateInstallShim : public update_client::CrxInstaller {
+ public:
+  // This method takes the id and root directory for an extension we're doing
+  // an update check for, as well as a callback to call if we get a new version
+  // of it to install.
+  UpdateInstallShim(std::string extension_id,
+                    const base::FilePath& extension_root,
+                    const UpdateInstallShimCallback& callback);
+
+  // Called when an update attempt failed.
+  void OnUpdateError(int error) override;
+
+  // This is called when a new version of an extension is unpacked at
+  // |unpack_path| and is ready for install.
+  bool Install(const base::DictionaryValue& manifest,
+               const base::FilePath& unpack_path) override;
+
+  // This is called by the generic differential update code in the
+  // update_client to provide the path to an existing file in the current
+  // version of the extension, so that it can be copied (or serve as the input
+  // to diff-patching) with output going to the directory with the new version
+  // being staged on disk for install.
+  bool GetInstalledFile(const std::string& file,
+                        base::FilePath* installed_file) override;
+
+  // This method is not relevant to extension updating.
+  bool Uninstall() override;
+
+ private:
+  friend class base::RefCountedThreadSafe<UpdateInstallShim>;
+  ~UpdateInstallShim() override;
+
+  // Takes ownership of the directory at path |temp_dir|.
+  void RunCallbackOnUIThread(const base::FilePath& temp_dir);
+
+  std::string extension_id_;
+  base::FilePath extension_root_;
+  UpdateInstallShimCallback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(UpdateInstallShim);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_UPDATER_UPDATE_INSTALL_SHIM_H_