Factor out authorization from AudioRendererHost.

content/browser/renderer_host/media/audio_output_authorization_handler.h

+// 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,
+                          media::AudioParameters,
+                          const std::string&)>;
+
+  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.
+  void RequestDeviceAuthorization(int render_frame_id,
+                                  int session_id,
+                                  const std::string& device_id,
+                                  const url::Origin& security_origin,
+                                  AuthorizationCompletedCallback cb);

[DaleCurtis, 2016/11/01 22:01:13]

"Pass `Callback` objects by value if ownership is transferred; otherwise, pass
it
by const-reference."

[Max Morin, 2016/11/02 11:47:06]

By value makes sense here. Since we bind it in another callback, we don't have
to reference-count if we move it, but we do if we bind it to a function taking a
const& (unless we use base::ConstRef, but base::ConstRef would leave a dangling
reference when we make thread hops). An added bonus is that migration to
OnceCallback is easy once the surrounding code is ready.

+
+  MediaDevicesPermissionChecker& GetMediaDevicesPermissionCheckerForTesting() {
+    return permission_checker_;
+  }
+
+ private:
+  void CheckOutputDeviceAccess(AuthorizationCompletedCallback cb,
+                               int render_frame_id,
+                               const std::string& device_id,
+                               const url::Origin& security_origin);
+
+  void AccessChecked(AuthorizationCompletedCallback cb,
+                     const std::string& device_id,
+                     const url::Origin& security_origin,
+                     bool have_access);
+
+  void TranslateDeviceID(AuthorizationCompletedCallback cb,
+                         const std::string& device_id,
+                         const url::Origin& security_origin,
+                         const MediaDeviceEnumeration& enumeration);
+
+  // |output_params| is passed by value since it's possibly mutated by this
+  // function, so it would have to be copied anyways.
+  void DeviceParametersReceived(AuthorizationCompletedCallback cb,
+                                bool device_found,
+                                const std::string& unique_id,
+                                media::AudioParameters output_params);
+
+  MediaStreamManager* const media_stream_manager_;
+  MediaDevicesPermissionChecker permission_checker_;
+  const int render_process_id_;
+  const std::string salt_;
+  base::WeakPtrFactory<AudioOutputAuthorizationHandler> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputAuthorizationHandler);
+};
+}  // namespace content
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_AUTHORIZATION_HANDLER_H_

[Avi (use Gerrit), 2016/11/01 15:06:34]

nit: two blank lines, one after the closing of the class, one after the closing
of the namespace.

[Max Morin, 2016/11/02 11:47:06]

Done.