[chrome.dial] Adds chrome.dial.fetchDeviceDecription API.

chrome/browser/extensions/api/dial/device_description_fetcher.h

+// Copyright (c) 2016 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_EXTENSIONS_API_DIAL_DEVICE_DESCRIPTION_FETCHER_H_
+#define CHROME_BROWSER_EXTENSIONS_API_DIAL_DEVICE_DESCRIPTION_FETCHER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/callback.h"
+#include "net/url_request/url_fetcher_delegate.h"
+#include "url/gurl.h"
+
+class Profile;
+
+namespace net {
+class URLFetcher;
+}
+
+namespace extensions {
+
+class DialDeviceDescription;
+
+// An instance of this class is used to make a single HTTP GET request with
+// |device_description_url| to fetch a uPnP device description.  If successful,
+// |success_cb| is invoked with the result; otherwise, |error_cb| is invoked
+// with an error reason.  This class is not thread safe.

[imcheng, 2016/12/28 05:36:45]

Also document on which thread the class is run on? (IO thread?)

[mark a. foltz, 2017/01/04 00:20:16]

Done.  Also use DCHECK_CURRENTLY_ON to enforce that it's accessed only from UI
thread.

+class DeviceDescriptionFetcher : public net::URLFetcherDelegate {
+ public:
+  // Used to identify the net::URLFetcher instance.
+  static constexpr int kURLFetcherID = 1;
+
+  DeviceDescriptionFetcher(
+      const GURL& device_description_url,
+      Profile* profile,
+      base::OnceCallback<void(const DialDeviceDescription&)> success_cb,
+      base::OnceCallback<void(const std::string&)> error_cb);
+
+  ~DeviceDescriptionFetcher() override;
+
+  void Start();
+
+ private:
+  // net::URLFetcherDelegate
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+  void OnURLFetchDownloadProgress(const net::URLFetcher* source,
+                                  int64_t current,
+                                  int64_t total,
+                                  int64_t current_network_bytes) override;
+  void OnURLFetchUploadProgress(const net::URLFetcher* source,
+                                int64_t current,
+                                int64_t total) override;
+
+  // Runs |error_cb_| with |message|.
+  void ReportError(const std::string& message);
+
+  const GURL device_description_url_;
+  Profile* profile_;

[imcheng, 2016/12/28 05:36:45]

Profile* const

[mark a. foltz, 2017/01/04 00:20:16]

Done.

+  base::OnceCallback<void(const DialDeviceDescription&)> success_cb_;
+  base::OnceCallback<void(const std::string&)> error_cb_;
+  std::unique_ptr<net::URLFetcher> fetcher_;
+
+  // TODO: Add a thread checker
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_DIAL_DEVICE_DESCRIPTION_FETCHER_H_