[Media Router] Add DialMediaSinkService and DeviceDescriptionService

chrome/browser/media/router/device_description_service.h

+// Copyright 2017 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_MEDIA_ROUTER_DEVICE_DESCRIPTION_SERVICE_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_DEVICE_DESCRIPTION_SERVICE_H_
+
+#include <memory>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/optional.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "chrome/browser/extensions/api/dial/dial_registry.h"

[mark a. foltz, 2017/03/11 00:08:15]

I wouldn't introduce a MR -> extensions dependency; instead suggest creating a
media/router/dial folder to hold dial_registry, device_description_fetcher, this
class, and other pieces shared between the extensions API and the MR.

Maybe discuss code location with imcheng@ and come up with a proposal?

[zhaobin, 2017/03/28 13:36:59]

Done.

+
+namespace extensions {
+namespace api {
+namespace dial {
+struct DialDeviceDescriptionData;
+class DeviceDescriptionFetcher;
+}
+}
+}
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace media_router {
+
+struct DialDeviceDescription {

[mark a. foltz, 2017/03/11 00:08:15]

We'll now have this struct, and DialDeviceData and DialDeviceDescriptionData
that is used by extensions::

I wonder if they can be combined somehow?

[zhaobin, 2017/04/10 18:44:41]

Created ParsedDialDeviceDescription struct with less fields.

+  DialDeviceDescription();
+  ~DialDeviceDescription();
+  DialDeviceDescription(const DialDeviceDescription& other);
+
+  std::string unique_id;

[mark a. foltz, 2017/03/11 00:08:15]

Please document the meanings of these fields.

[zhaobin, 2017/03/28 13:36:59]

Done.

+  std::string device_label;
+  std::string friendly_name;
+  std::string ip_address;
+  GURL app_url;
+  base::Time fetch_time_millis;
+  base::Time expire_time_millis;
+  std::string device_type;

[mark a. foltz, 2017/03/11 00:08:15]

Should this be an enum?

[zhaobin, 2017/03/28 13:36:59]

Seems like a string according to
spec...http://upnp.org/specs/arch/UPnP-arch-DeviceArchitecture-v2.0.pdf

+  std::string model_name;
+  base::Optional<int32_t> config_id;
+};
+
+class DeviceDescriptionService {
+ public:
+  using DialRegistry = extensions::api::dial::DialRegistry;
+  using DialDeviceDescriptionData =
+      extensions::api::dial::DialDeviceDescriptionData;
+  using DialDeviceData = extensions::api::dial::DialDeviceData;
+
+  class Observer {
+   public:
+    // Methods invoked on the IO thread when device description fetch for
+    // |device_id| completed.
+    virtual void OnDeviceDescriptionAvailable(
+        const std::string& device_id,
+        const DialDeviceDescription& description) = 0;
+    virtual void OnDeviceDescriptionFetchError(
+        const std::string& device_id,
+        const std::string& error_message) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  // This class does not take ownership of |observer|.
+  explicit DeviceDescriptionService(Observer* observer);
+  ~DeviceDescriptionService();
+
+  // Returns true and sets |out_description| to cached device description if
+  // there is a valid cache entry; Returns false and start device description
+  // fetch otherwise.
+  bool GetDeviceDescription(const DialDeviceData& device,
+                            net::URLRequestContextGetter* request_context,
+                            DialDeviceDescription* out_description);
+
+  // Returns false if there is no pending fetcher for |device_label|.
+  bool MayStopDeviceDescriptionFetching(const std::string& device_label);
+
+ private:
+  // Issues a HTTP GET request for the device description. No-op if there is
+  // already a pending request.
+  void FetchDeviceDescription(const DialDeviceData& dial_device,
+                              net::URLRequestContextGetter* request_context);
+
+  // Checks the cache for a valid device description.  If the entry is found but
+  // is no longer valid, it is removed from the cache.
+  // |dial_device|: the device to look up.
+  // Returns nullptr if cache entry does not exist or is not valid.
+  bool CheckAndUpdateCache(const DialDeviceData& dial_device,
+                           DialDeviceDescription* out_description);
+
+  // Processes the result of getting device description and adds the device
+  // description to the cache.
+  // TODO(imcheng): Also cache permanent failures (b/32976125).
+  // |dial_device|: Device data from device discovery.
+  // |xml_text|: The device description.
+  // |app_url|: The application URL.
+  // Returns true and populates corresponding fields in |description| if
+  // processing succeeds; Returns false if processing fails.
+  bool ProcessDeviceDescription(const DialDeviceData& dial_device,
+                                const std::string& xmlText,
+                                const GURL& app_url,
+                                DialDeviceDescription* description);
+
+  // Parses a device description document into a DialDeviceDescription object.
+  // |dial_device|: Device data from device discovery.
+  // |xml_text|: The device description.
+  // |app_url|: The application URL.
+  // Returns true and populates corresponding fields in |description| if parsing
+  // succeeds; Returns false if parsing fails.
+  bool ParseDeviceDescription(const DialDeviceData& dial_device,
+                              const std::string& xml_text,
+                              const GURL& app_url,
+                              DialDeviceDescription* description);
+
+  // Invoked when HTTP GET request finishes.
+  // |dial_device|: Device data initiating the HTTP request.
+  // |description_data|: Response from HTTP request.
+  void OnDeviceDescriptionAvailable(
+      const DialDeviceData& dial_device,
+      const DialDeviceDescriptionData& description_data);
+
+  // Invoked when HTTP GET request fails.
+  // |dial_device|: Device data initiating the HTTP request.
+  void OnDeviceDescriptionFetchError(const DialDeviceData& dial_device,
+                                     const std::string& error_message);
+
+  // device label, DeviceDescriptionFetcher
+  std::map<std::string,
+           std::unique_ptr<extensions::api::dial::DeviceDescriptionFetcher>>
+      device_description_fetcher_map_;
+
+  // device label, DialDeviceDescription
+  std::map<std::string, DialDeviceDescription> description_map_;
+
+  // This class does not take ownership of |observer_|
+  Observer* observer_;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_DEVICE_DESCRIPTION_SERVICE_H_