Support audio output device enumeration and selection in PPAPI

ppapi/proxy/audio_output_resource.h

Index: ppapi/proxy/audio_output_resource.h
diff --git a/ppapi/proxy/audio_output_resource.h b/ppapi/proxy/audio_output_resource.h
new file mode 100644
index 0000000000000000000000000000000000000000..ee654e1c2e07b46c9b1cf2f7095c736d4d41e6ba
--- /dev/null
+++ b/ppapi/proxy/audio_output_resource.h
@@ -0,0 +1,149 @@
+// Copyright (c) 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 PPAPI_PROXY_AUDIO_OUTPUT_RESOURCE_H_
+#define PPAPI_PROXY_AUDIO_OUTPUT_RESOURCE_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/shared_memory.h"
+#include "base/sync_socket.h"
+#include "base/threading/simple_thread.h"
+#include "ppapi/c/ppb_audio_config.h"
+#include "ppapi/proxy/device_enumeration_resource_helper.h"
+#include "ppapi/proxy/plugin_resource.h"
+#include "ppapi/shared_impl/scoped_pp_resource.h"
+#include "ppapi/thunk/ppb_audio_output_api.h"
+
+namespace media {
+class AudioBus;
+}
+
+namespace ppapi {
+namespace proxy {
+
+class ResourceMessageReplyParams;
+
+class AudioOutputResource : public PluginResource,
+                            public thunk::PPB_AudioOutput_API,
+                            public base::DelegateSimpleThread::Delegate {
+ public:
+  AudioOutputResource(Connection connection, PP_Instance instance);
+  ~AudioOutputResource() override;
+
+  // Resource overrides.
+  thunk::PPB_AudioOutput_API* AsPPB_AudioOutput_API() override;
+  void OnReplyReceived(const ResourceMessageReplyParams& params,
+                       const IPC::Message& msg) override;
+
+  // PPB_AudioOutput_API implementation.
+  int32_t EnumerateDevices(const PP_ArrayOutput& output,
+                           scoped_refptr<TrackedCallback> callback) override;
+  int32_t MonitorDeviceChange(PP_MonitorDeviceChangeCallback callback,
+                              void* user_data) override;
+  int32_t Open(PP_Resource device_ref,
+               PP_Resource config,
+               PPB_AudioOutput_Callback audio_output_callback,
+               void* user_data,
+               scoped_refptr<TrackedCallback> callback) override;
+
+  PP_Resource GetCurrentConfig() override;
+
+  bool playing() const { return playing_; }
+
+  PP_Bool StartPlayback() override;
+  PP_Bool StopPlayback() override;
+  void Close() override;
+
+ protected:
+  // Resource override.
+  void LastPluginRefWasDeleted() override;
+
+ private:
+  enum OpenState { BEFORE_OPEN, OPENED, CLOSED };
+
+  void OnPluginMsgOpenReply(const ResourceMessageReplyParams& params);
+
+  // Sets the shared memory and socket handles.
+  void SetStreamInfo(base::SharedMemoryHandle shared_memory_handle,
+                     size_t shared_memory_size,
+                     base::SyncSocket::Handle socket_handle);
+
+  // Starts execution of the audio output thread.
+  void StartThread();
+
+  // Stops execution of the audio output thread.
+  void StopThread();
+
+  // DelegateSimpleThread::Delegate implementation.
+  // Run on the audio output thread.
+  void Run() override;
+
+  int32_t CommonOpen(PP_Resource device_ref,
+                     PP_Resource config,
+                     PPB_AudioOutput_Callback audio_output_callback,
+                     void* user_data,
+                     scoped_refptr<TrackedCallback> callback);
+
+  OpenState open_state_;
+
+  // True if playing the stream.
+  bool playing_;
+
+  // Socket used to notify us when new samples are available. This pointer is
+  // created in SetStreamInfo().
+  std::unique_ptr<base::CancelableSyncSocket> socket_;
+
+  // Sample buffer in shared memory. This pointer is created in
+  // SetStreamInfo(). The memory is only mapped when the audio thread is
+  // created.
+  std::unique_ptr<base::SharedMemory> shared_memory_;
+
+  // The size of the sample buffer in bytes.
+  size_t shared_memory_size_;
+
+  // When the callback is set, this thread is spawned for calling it.
+  std::unique_ptr<base::DelegateSimpleThread> audio_output_thread_;
+
+  // Callback to call when new samples are available.
+  PPB_AudioOutput_Callback audio_output_callback_;
+
+  // User data pointer passed verbatim to the callback function.
+  void* user_data_;
+
+  // The callback is not directly passed to OnPluginMsgOpenReply() because we
+  // would like to be able to cancel it early in Close().
+  scoped_refptr<TrackedCallback> open_callback_;
+
+  // Owning reference to the current config object. This isn't actually used,
+  // we just dish it out as requested by the plugin.
+  ScopedPPResource config_;
+
+  DeviceEnumerationResourceHelper enumeration_helper_;
+
+  // The data size (in bytes) of one second of audio output. Used to calculate
+  // latency.
+  size_t bytes_per_second_;
+
+  // AudioBus for shuttling data across the shared memory.
+  std::unique_ptr<media::AudioBus> audio_bus_;
+  int sample_frame_count_;
+
+  // Internal buffer for client's integer audio data.
+  int client_buffer_size_bytes_;
+  std::unique_ptr<uint8_t[]> client_buffer_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputResource);
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+#endif  // PPAPI_PROXY_AUDIO_OUTPUT_RESOURCE_H_