Verify the signature on user cloud policy downloads.

chrome/browser/policy/user_policy_key.cc

Index: chrome/browser/policy/user_policy_key.cc
diff --git a/chrome/browser/policy/user_policy_key.cc b/chrome/browser/policy/user_policy_key.cc
new file mode 100644
index 0000000000000000000000000000000000000000..45e5d7b6a51fcb7a42305d3a381417d07447c9e8
--- /dev/null
+++ b/chrome/browser/policy/user_policy_key.cc
@@ -0,0 +1,73 @@
+// 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.
+
+#include "chrome/browser/policy/user_policy_key.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/callback.h"
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/stl_util.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace policy {
+
+namespace {
+
+const int kKeySizeLimit = 16 * 1024;
+
+void LoadKey(const FilePath& path, std::vector<uint8>* key) {
+  if (!file_util::PathExists(path)) {
+    VLOG(1) << "No key at " << path.value();
+    return;
+  }
+
+  int64 size;
+  if (!file_util::GetFileSize(path, &size)) {
+    LOG(ERROR) << "Could not get size of " << path.value();
+  } else if (size == 0 || size > kKeySizeLimit) {
+    LOG(ERROR) << "Key at " << path.value() << " has bad size " << size;
+  } else {
+    key->resize(size);
+    int read_size = file_util::ReadFile(
+        path, reinterpret_cast<char*>(vector_as_array(key)), size);
+    if (read_size != size) {
+      LOG(ERROR) << "Failed to read key at " << path.value();
+      key->clear();
+    }
+  }
+}
+
+}  // namespace
+
+UserPolicyKey::UserPolicyKey(const FilePath& path)
+    : path_(path),
+      ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {}
+
+UserPolicyKey::~UserPolicyKey() {
+  DCHECK(CalledOnValidThread());
+}
+
+void UserPolicyKey::Load(const base::Closure& callback) {
+  DCHECK(CalledOnValidThread());
+  std::vector<uint8>* key = new std::vector<uint8>();
+  content::BrowserThread::PostBlockingPoolTaskAndReply(
+      FROM_HERE,
+      base::Bind(&LoadKey, path_, key),
+      base::Bind(&UserPolicyKey::OnKeyLoaded,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 base::Owned(key),
+                 callback));
+}
+
+void UserPolicyKey::OnKeyLoaded(std::vector<uint8>* key,
+                                const base::Closure& callback) {
+  DCHECK(CalledOnValidThread());
+  key_.swap(*key);
+  MessageLoop::current()->PostTask(FROM_HERE, callback);
+}
+
+}  // namespace policy