Implement support for fallback update check urls in the component updater

components/component_updater/request_sender.h

+// Copyright 2014 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 COMPONENTS_COMPONENT_UPDATER_REQUEST_SENDER_H_
+#define COMPONENTS_COMPONENT_UPDATER_REQUEST_SENDER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"

[erikwright (departed), 2014/09/15 18:37:11]

I believe "base/macros.h" is preferred over "base/basictypes.h"

[Sorin Jianu, 2014/09/15 22:17:57]

Thank you. Fixed here and I will fix the rest of the module in a future CL.

[erikwright (departed), 2014/09/16 17:38:11]

I wouldn't worry about fixing files you aren't already touching.

[Sorin Jianu, 2014/09/16 19:53:31]

Acknowledged.

+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/url_request/url_fetcher.h"

[erikwright (departed), 2014/09/15 18:37:11]

can be forward-decl.

[Sorin Jianu, 2014/09/15 22:17:57]

Done.

+#include "net/url_request/url_fetcher_delegate.h"
+#include "url/gurl.h"
+
+namespace component_updater {
+
+class Configurator;
+
+// Sends a request to one of the urls provided. The class implements a chain
+// of responsibility design pattern, where the urls are tried in the order they
+// are specified, until the request to one of them succeeds or all have failed.
+class RequestSender : public net::URLFetcherDelegate {
+ public:
+  // The |source| refers to the fetcher object used to make the request. This
+  // parameter can be NULL in some error cases.
+  typedef base::Callback<void(const net::URLFetcher* source)>
+      RequestSenderCallback;
+
+  explicit RequestSender(const Configurator& config);
+  virtual ~RequestSender();
+
+  void Send(const std::string& request_string,
+            const std::vector<GURL>& urls,
+            const RequestSenderCallback& request_sender_callback);
+
+ private:
+  void SendInternal();
+
+  // Overrides for URLFetcherDelegate.
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
+
+  const Configurator& config_;

[erikwright (departed), 2014/09/15 18:37:11]

reference members are not that common in the Chromium codebase, but I couldn't
find a prohibition on them.

[Sorin Jianu, 2014/09/15 22:17:57]

Acknowledged.

+  std::vector<GURL> urls_;
+  std::vector<GURL>::const_iterator cur_url_;
+  scoped_ptr<net::URLFetcher> url_fetcher_;
+  std::string request_string_;
+  RequestSenderCallback request_sender_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(RequestSender);
+};
+
+}  // namespace component_updater
+
+#endif  // COMPONENTS_COMPONENT_UPDATER_REQUEST_SENDER_H_