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..5a5b043ed03afeae84578abdb3d287983265d8cd
--- /dev/null
+++ b/content/browser/renderer_host/media/audio_output_authorization_handler.h
@@ -0,0 +1,92 @@
+// 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 =

[o1ka, 2016/11/03 10:07:22]

Please explain parameters meaning in the comment - it's really unclear,
specially what to expect in "string" part.

[Max Morin, 2016/11/10 14:59:52]

I added this to the comment on RequestDeviceAuthorization.

+      base::Callback<void(media::OutputDeviceStatus,
+                          const 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,

[o1ka, 2016/11/03 10:07:22]

const method?

[Max Morin, 2016/11/10 14:59:52]

Done.

+                                  int session_id,
+                                  const std::string& device_id,
+                                  const url::Origin& security_origin,
+                                  AuthorizationCompletedCallback cb);
+
+  MediaDevicesPermissionChecker& GetMediaDevicesPermissionCheckerForTesting() {

[o1ka, 2016/11/03 10:07:22]

I feel like it should be const ref. Probably fix MediaDevicesPermissionChecker
to have all methods as const?

[Max Morin, 2016/11/10 14:59:52]

The purpose was actually to allow the caller to modify
MediaDevicesPermissionChecker (add override), I added a simpler method instead
of this one.

+    return permission_checker_;
+  }
+
+ private:
+  void CheckOutputDeviceAccess(AuthorizationCompletedCallback cb,

[o1ka, 2016/11/03 10:07:22]

all methods const?

[Max Morin, 2016/11/10 14:59:52]

Done.

+                               int render_frame_id,
+                               const std::string& device_id,
+                               const url::Origin& security_origin);
+
+  void AccessChecked(AuthorizationCompletedCallback cb,

[o1ka, 2016/11/03 10:07:22]

We need to explain each of the methods here.

[Max Morin, 2016/11/10 14:59:52]

I added an overview of how the implementation of RequestDeviceAuthorization
works. The individual methods doesn't make sense in isolation, it's more like
the entire class is one long function that had to be divided into pieces due to
async calls. It could be divided into functions in a way that makes sense, but
as discussed offline, it's not a priority right now.

+                     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,
+                                const 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_