Factor out authorization from AudioRendererHost.

content/browser/renderer_host/media/audio_output_authorization_handler.h

Index: content/browser/renderer_host/media/audio_output_authorization_handler.h
diff --git a/content/browser/renderer_host/media/audio_output_authorization_handler.h b/content/browser/renderer_host/media/audio_output_authorization_handler.h
new file mode 100644
index 0000000000000000000000000000000000000000..be6fb576886b0fe751475d170d8e6c4d3e10ddb4
--- /dev/null
+++ b/content/browser/renderer_host/media/audio_output_authorization_handler.h
@@ -0,0 +1,108 @@
+// Copyright 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.
+
+// This class implements authorization checking for AudioRendererHost.
+#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_AUTHORIZATION_HANDLER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_AUTHORIZATION_HANDLER_H_
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/callback_forward.h"
+#include "base/memory/weak_ptr.h"
+#include "content/browser/media/media_devices_permission_checker.h"
+#include "content/browser/renderer_host/media/media_stream_manager.h"
+#include "media/audio/audio_device_description.h"
+#include "media/audio/audio_manager.h"
+#include "media/base/audio_parameters.h"
+#include "media/base/output_device_info.h"
+
+namespace content {
+
+// This class, which lives on the IO thread, handles the logic of an IPC device
+// request from the renderer. It checks which device to use (in case of using
+// session_id to select device), verifies that the renderer is authorized to use
+// the device, and gets the default device parameters for the selected audio
+// device.
+class CONTENT_EXPORT AudioOutputAuthorizationHandler {
+ public:
+  // TODO(maxmorin): Change to OnceCallback once base:: code is ready for it.
+  using AuthorizationCompletedCallback =
+      base::Callback<void(media::OutputDeviceStatus status,

[o1ka, 2016/11/14 13:24:04]

Explain parameters meaning?

[Max Morin, 2016/11/16 08:49:49]

Done.

+                          const media::AudioParameters& params,
+                          const std::string& translated_device_id)>;
+
+  AudioOutputAuthorizationHandler(MediaStreamManager* media_stream_manager,
+                                  int render_process_id_,
+                                  const std::string& salt);
+
+  ~AudioOutputAuthorizationHandler();
+
+  // Checks authorization of the device with the hashed id device_id for the
+  // given render frame id and security origin, or uses session_id for
+  // authorization. Looks up device id (if session_id is used for device
+  // selection) and default device parameters. |cb| will be called with the
+  // result by |this| on the IO thread. The device_id returned in the callback
+  // will be translated, i.e. not hashed.
+  void RequestDeviceAuthorization(int render_frame_id,
+                                  int session_id,
+                                  const std::string& device_id,
+                                  const url::Origin& security_origin,
+                                  AuthorizationCompletedCallback cb) const;
+
+  void OverridePermissionsForTesting(bool override_value);
+
+ private:
+  // A simplified overview of implementation:
+  // RequestDeviceAuthorization:
+  //   Check if session_id should be used. If yes, fetch saved device and
+  //   parameters and we can skip to DeviceParametersRecieved. Otherwise,
+  //   check whether the renderer has access to the output device
+  //   (async in case of a nondefault device). Result goes to AccessChecked.
+  // AccessChecked:
+  //   Queries audio parameters for default devices and calls
+  //   DeviceParametersRecieved. Nondefault devices go
+  //   through TranslateDeviceID.
+  // TranslateDeviceID:

[o1ka, 2016/11/14 13:24:04]

Could you make it per-function and explain parameter meaning as well? It's still
not clear which id this function takes.

[Max Morin, 2016/11/16 08:49:49]

Done.

+  //   Checks which raw device id corresponds to the hashed device_id,
+  //   and then gets default parameters for it and calls
+  //   DeviceParametersRecieved with the parameters and the translated id.
+  // DeviceParametersRecieved:
+  //   Returns by calling the callback.
+  //
+  // This sequence of calls can be broken at various places, e.g. if access
+  // rights are missing or the device cannot be found. In this case, a non-Ok
+  // status indicating the error is returned through the callback.
+
+  void AccessChecked(AuthorizationCompletedCallback cb,
+                     const std::string& device_id,
+                     const url::Origin& security_origin,
+                     bool have_access) const;
+
+  void TranslateDeviceID(AuthorizationCompletedCallback cb,
+                         const std::string& device_id,
+                         const url::Origin& security_origin,
+                         const MediaDeviceEnumeration& enumeration) const;
+
+  void DeviceParametersReceived(
+      AuthorizationCompletedCallback cb,
+      const std::string& translated_device_id,
+      const media::AudioParameters& output_params) const;
+
+  MediaStreamManager* const media_stream_manager_;
+  std::unique_ptr<MediaDevicesPermissionChecker> permission_checker_;
+  const int render_process_id_;
+  const std::string salt_;
+  // All access is on IO thread, and taking a weak pointer to const looks
+  // const, so this can be mutable.
+  mutable base::WeakPtrFactory<const AudioOutputAuthorizationHandler>
+      weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputAuthorizationHandler);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_AUTHORIZATION_HANDLER_H_