Add a header when fetching pages under the DMServer URL.

components/policy/core/browser/policy_header_io_helper.cc

+// 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 "components/policy/core/browser/policy_header_io_helper.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/sequenced_task_runner.h"
+#include "net/url_request/url_request.h"
+
+namespace {
+
+// The name of the header containing the policy information.
+const char kChromePolicyHeader[] = "Chrome-Policy-Posture";
+
+}  // namespace
+
+namespace policy {
+
+PolicyHeaderIOHelper::PolicyHeaderIOHelper(
+    const std::string& server_url,
+    const std::string& initial_header_value,
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : server_url_(server_url),
+      task_runner_(task_runner),
+      policy_header_(initial_header_value),
+      weak_factory_(this) {
+}
+
+PolicyHeaderIOHelper::~PolicyHeaderIOHelper() {
+}
+
+// Sets any necessary policy headers on the passed request.
+void PolicyHeaderIOHelper::AddPolicyHeaders(net::URLRequest* request) const {
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+  const GURL& url = request->url();
+  if (!policy_header_.empty() &&
+      url.spec().compare(0, server_url_.size(), server_url_) == 0) {
+    request->SetExtraRequestHeaderByName(kChromePolicyHeader,
+                                         policy_header_,
+                                         true /* overwrite */);
+  }
+}
+
+void PolicyHeaderIOHelper::UpdateHeader(const std::string& new_header) {
+  // Post a task to the IO thread to modify this.
+  task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&PolicyHeaderIOHelper::UpdateHeaderOnTaskRunner,

[willchan no longer on Chromium, 2013/12/10 23:32:14]

Suggestions:
s/task_runner_/io_task_runner_/
s/UpdateHeaderOnTaskRunner/UpdateHeaderOnIOThread/

I don't think there's an advantage to being generic in naming here, since use of
this object is fairly tightly coupled to assumptions around content/'s threading
architecture.

[Andrew T Wilson (Slow), 2013/12/10 23:53:06]

Done. This was my original intent, but I got pushback from another reviewer. But
since I agree with you, I'm changing this back to be more specific :)

+                 weak_factory_.GetWeakPtr(), new_header));
+}
+
+void PolicyHeaderIOHelper::UpdateHeaderOnTaskRunner(
+    const std::string& new_header) {
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+  policy_header_ = new_header;
+}
+
+}  // namespace policy