Verify the signature on user cloud policy downloads.

chrome/browser/policy/user_policy_key.h

+// Copyright (c) 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 CHROME_BROWSER_POLICY_USER_POLICY_KEY_H_
+#define CHROME_BROWSER_POLICY_USER_POLICY_KEY_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/non_thread_safe.h"
+
+namespace policy {
+
+class UserPolicyKey : public base::NonThreadSafe {

[Mattias Nissler (ping if slow), 2013/02/07 14:12:07]

Not quite convinced putting this into its own class is justified after all. It's
more or less a glorified ReadFileToVector(), executing on a blocking bool
thread. How about just doing a static scoped_ptr<std::vector<uint8>>
UserPolicyStoreChromeOS::LoadPolicyKey(const FilePath& path) that you can fire
on the blocking pool?

[Joao da Silva, 2013/02/07 16:32:00]

Done.

+ public:
+  explicit UserPolicyKey(const FilePath& path);
+  ~UserPolicyKey();
+
+  // Reloads the user policy key from |path_|, and posts |callback| to the
+  // message loop that owns the object.
+  void Load(const base::Closure& callback);
+
+  const std::vector<uint8>& key() const { return key_; }
+
+ private:
+  void OnKeyLoaded(std::vector<uint8>* key, const base::Closure& callback);
+
+  FilePath path_;
+  std::vector<uint8> key_;
+  base::WeakPtrFactory<UserPolicyKey> weak_ptr_factory_;

[Mattias Nissler (ping if slow), 2013/02/07 14:12:07]

DISALLOw_COPY_AND_ASSIGN?

+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_POLICY_USER_POLICY_KEY_H_