Add mojo interface+impl creation of audio streams.

content/browser/renderer_host/media/renderer_audio_output_stream_factory_context.h

Index: content/browser/renderer_host/media/renderer_audio_output_stream_factory_context.h
diff --git a/content/browser/renderer_host/media/renderer_audio_output_stream_factory_context.h b/content/browser/renderer_host/media/renderer_audio_output_stream_factory_context.h
new file mode 100644
index 0000000000000000000000000000000000000000..180aaad2023b7a063a3352a3170488c77a041eee
--- /dev/null
+++ b/content/browser/renderer_host/media/renderer_audio_output_stream_factory_context.h
@@ -0,0 +1,57 @@
+// 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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_RENDERER_AUDIO_OUTPUT_STREAM_FACTORY_CONTEXT_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_RENDERER_AUDIO_OUTPUT_STREAM_FACTORY_CONTEXT_H_
+
+#include <memory>
+#include <string>
+
+#include "content/browser/renderer_host/media/audio_output_authorization_handler.h"
+#include "content/common/content_export.h"
+#include "media/audio/audio_output_delegate.h"
+
+namespace media {
+class AudioParameters;
+}
+
+namespace url {
+class Origin;
+}
+
+namespace content {
+
+// RendererAudioOutputStreamFactoryContext provides functions common to all

[DaleCurtis, 2017/03/24 17:47:12]

This is technically descriptive but doesn't really talk about the purpose of the
class.

+// AudioOutputFactory instances for a single renderer process.
+class CONTENT_EXPORT RendererAudioOutputStreamFactoryContext {
+ public:
+  virtual ~RendererAudioOutputStreamFactoryContext() {}
+
+  using AuthorizationCompletedCallback =
+      AudioOutputAuthorizationHandler::AuthorizationCompletedCallback;
+
+  virtual int GetRenderProcessId() const = 0;
+
+  virtual std::string GetHMACForDeviceId(

[DaleCurtis, 2017/03/24 17:47:12]

Seems like this should also be UnguesableToken in the future.

[Max Morin, 2017/03/27 14:40:51]

It makes sense, but this would require us to store a map (origin, device_id) ->
(token). It must also be stored between browser sessions (not sure how this
works today). On the plus side, the device_id as visible to the renderer will be
of a different type from the device_id we use when interacting with the audio
manager, which would reduce confusion.

+      const url::Origin& origin,
+      const std::string& raw_device_id) const = 0;
+
+  // Called to request access to a device on behalf of the renderer.
+  virtual void RequestDeviceAuthorization(
+      int render_frame_id,
+      int session_id,
+      const std::string& device_id,
+      const url::Origin& security_origin,
+      AuthorizationCompletedCallback cb) const = 0;
+
+  virtual std::unique_ptr<media::AudioOutputDelegate> CreateDelegate(
+      const std::string& unique_device_id,
+      int render_frame_id,
+      const media::AudioParameters& params,
+      media::AudioOutputDelegate::EventHandler* handler) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_RENDERER_AUDIO_OUTPUT_STREAM_FACTORY_CONTEXT_H_