Add mojo interface+impl creation of audio streams.

content/browser/renderer_host/media/render_frame_audio_output_stream_factory.h

Index: content/browser/renderer_host/media/render_frame_audio_output_stream_factory.h
diff --git a/content/browser/renderer_host/media/render_frame_audio_output_stream_factory.h b/content/browser/renderer_host/media/render_frame_audio_output_stream_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..bdfcf2034f87bc83d2bf21f7ae3b51cc570c2256
--- /dev/null
+++ b/content/browser/renderer_host/media/render_frame_audio_output_stream_factory.h
@@ -0,0 +1,66 @@
+// 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_RENDER_FRAME_AUDIO_OUTPUT_STREAM_FACTORY_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_RENDER_FRAME_AUDIO_OUTPUT_STREAM_FACTORY_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "content/common/content_export.h"
+#include "content/common/media/renderer_audio_output_stream_factory.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace content {
+
+class RendererAudioOutputStreamFactoryContext;
+
+// Handles a RendererAudioOutputStreamFactory request for a render frame host,

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

Again technically descriptive, but doesn't really say what it does. 

+// using the provided RendererAudioOutputStreamFactoryContext.
+class CONTENT_EXPORT RenderFrameAudioOutputStreamFactory
+    : public mojom::RendererAudioOutputStreamFactory {
+ public:
+  RenderFrameAudioOutputStreamFactory(
+      RendererAudioOutputStreamFactoryContext* context,
+      int render_frame_id);
+
+  ~RenderFrameAudioOutputStreamFactory() override;
+
+ private:
+  using OutputStreamProviderVector =
+      std::vector<std::unique_ptr<media::mojom::AudioOutputStreamProvider>>;
+
+  // mojom::RendererAudioOutputStreamFactory implementation.
+  void RequestDeviceAuthorization(
+      media::mojom::AudioOutputStreamProviderRequest stream_provider,
+      int64_t session_id,

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

For session_id, should we start using base::UnguessableToken?

[Max Morin, 2017/03/27 14:40:50]

Replied to a comment in cc file.

+      const std::string& device_id,
+      const url::Origin& origin,
+      const RequestDeviceAuthorizationCallback& callback) override;
+
+  void AuthorizationCompleted(
+      const url::Origin& origin,
+      base::TimeTicks auth_start_time,
+      media::mojom::AudioOutputStreamProviderRequest request,
+      const RequestDeviceAuthorizationCallback& callback,
+      media::OutputDeviceStatus status,
+      bool should_send_id,
+      const media::AudioParameters& params,
+      const std::string& raw_device_id);
+
+  void RemoveStream(media::mojom::AudioOutputStreamProvider* stream_provider);
+
+  base::ThreadChecker thread_checker_;
+  RendererAudioOutputStreamFactoryContext* const context_;
+  // The stream providers will contain the corresponding streams.
+  OutputStreamProviderVector stream_providers_;
+  const int render_frame_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderFrameAudioOutputStreamFactory);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_RENDER_FRAME_AUDIO_OUTPUT_STREAM_FACTORY_H_