Tab Audio Mirroring: WebContentsAudioInputStream is a new implementation which represents the lifet…

content/browser/renderer_host/media/web_contents_audio_input_stream.cc

+// Copyright (c) 2013 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.
+
+#include "content/browser/renderer_host/media/web_contents_audio_input_stream.h"
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop_proxy.h"
+#include "content/browser/browser_main_loop.h"
+#include "content/browser/renderer_host/media/audio_mirroring_manager.h"
+#include "content/browser/renderer_host/media/web_contents_capture_util.h"
+#include "content/browser/renderer_host/media/web_contents_tracker.h"
+#include "content/public/browser/browser_thread.h"
+#include "media/audio/virtual_audio_input_stream.h"
+#include "media/audio/virtual_audio_output_stream.h"
+
+namespace content {
+
+class WebContentsAudioInputStream::Impl
+    : public base::RefCountedThreadSafe<WebContentsAudioInputStream::Impl>,
+      public AudioMirroringManager::MirroringDestination {
+ public:
+  // Takes ownership of |mixer_stream|.  The rest outlive this instance.
+  Impl(int render_process_id, int render_view_id,
+       base::MessageLoopProxy* message_loop,
+       AudioMirroringManager* mirroring_manager,
+       const scoped_refptr<WebContentsTracker>& tracker,
+       media::VirtualAudioInputStream* mixer_stream);
+
+  // Open underlying VirtualAudioInputStream and start tracker.
+  bool Open();
+
+  // Start the underlying VirtualAudioInputStream and instruct
+  // AudioMirroringManager to begin a mirroring session.
+  void Start(AudioInputCallback* callback);
+
+  // Stop the underlying VirtualAudioInputStream and instruct
+  // AudioMirroringManager to shutdown a mirroring session.
+  void Stop();
+
+  // Close the underlying VirtualAudioInputStream and stop the tracker.
+  void Close();
+
+  // Accessor to underlying VirtualAudioInputStream.
+  media::VirtualAudioInputStream* mixer_stream() const {
+    return mixer_stream_.get();
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<WebContentsAudioInputStream::Impl>;
+
+  enum State {
+    CONSTRUCTED,
+    OPENED,
+    MIRRORING,
+    CLOSED
+  };
+
+  virtual ~Impl();
+
+  // Returns true if the mirroring target has been permanently lost.
+  bool IsTargetLost() const;
+
+  // Notifies the consumer callback that the stream is now dead.
+  void ReportError();
+
+  // Start/Stop mirroring by posting a call to AudioMirroringManager on the IO
+  // BrowserThread.
+  void StartMirroring();
+  void StopMirroring();
+
+  // AudioMirroringManager::MirroringDestination implementation
+  virtual media::AudioOutputStream* AddInput(
+      const media::AudioParameters& params) OVERRIDE;
+
+  // Callback which is run when |stream| is closed.  Deletes |stream|.
+  void ReleaseInput(media::VirtualAudioOutputStream* stream);
+
+  // Called by WebContentsTracker when the target of the audio mirroring has
+  // changed.
+  void OnTargetChanged(int render_process_id, int render_view_id);
+
+  // Injected dependencies.
+  base::MessageLoopProxy* const message_loop_;
+  AudioMirroringManager* const mirroring_manager_;
+  const scoped_refptr<WebContentsTracker> tracker_;
+  // The AudioInputStream implementation that handles the audio conversion and
+  // mixing details.
+  const scoped_ptr<media::VirtualAudioInputStream> mixer_stream_;
+
+  State state_;
+
+  // Current audio mirroring target.
+  int target_render_process_id_;
+  int target_render_view_id_;
+
+  // Current callback used to consume the resulting mixed audio data.
+  AudioInputCallback* callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(Impl);
+};
+
+WebContentsAudioInputStream::Impl::Impl(
+    int render_process_id, int render_view_id,
+    base::MessageLoopProxy* message_loop,
+    AudioMirroringManager* mirroring_manager,
+    const scoped_refptr<WebContentsTracker>& tracker,
+    media::VirtualAudioInputStream* mixer_stream)
+    : message_loop_(message_loop), mirroring_manager_(mirroring_manager),
+      tracker_(tracker), mixer_stream_(mixer_stream), state_(CONSTRUCTED),
+      target_render_process_id_(render_process_id),
+      target_render_view_id_(render_view_id),
+      callback_(NULL) {
+  DCHECK(message_loop_);
+  DCHECK(mirroring_manager_);
+  DCHECK(tracker_);
+  DCHECK(mixer_stream_.get());
+}
+
+WebContentsAudioInputStream::Impl::~Impl() {
+  DCHECK(state_ == CONSTRUCTED || state_ == CLOSED);
+}
+
+bool WebContentsAudioInputStream::Impl::Open() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  DCHECK_EQ(CONSTRUCTED, state_) << "Illegal to Open more than once.";
+
+  if (!mixer_stream_->Open())
+    return false;
+
+  state_ = OPENED;
+
+  tracker_->Start(
+      target_render_process_id_, target_render_view_id_,
+      base::Bind(&Impl::OnTargetChanged, this));
+
+  return true;
+}
+
+void WebContentsAudioInputStream::Impl::Start(AudioInputCallback* callback) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  DCHECK(callback);
+
+  if (state_ != OPENED)
+    return;
+
+  if (IsTargetLost()) {
+    ReportError();
+    return;
+  }
+
+  state_ = MIRRORING;
+
+  callback_ = callback;
+  mixer_stream_->Start(callback);
+
+  StartMirroring();
+}
+
+void WebContentsAudioInputStream::Impl::Stop() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  if (state_ != MIRRORING)
+    return;
+
+  state_ = OPENED;
+
+  mixer_stream_->Stop();
+  callback_ = NULL;
+
+  if (!IsTargetLost())
+    StopMirroring();
+}
+
+void WebContentsAudioInputStream::Impl::Close() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  Stop();
+
+  if (state_ == OPENED) {
+    state_ = CONSTRUCTED;
+    tracker_->Stop();
+    mixer_stream_->Close();
+  }
+
+  DCHECK_EQ(CONSTRUCTED, state_);
+  state_ = CLOSED;
+}
+
+bool WebContentsAudioInputStream::Impl::IsTargetLost() const {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  return target_render_process_id_ <= 0 || target_render_view_id_ <= 0;
+}
+
+void WebContentsAudioInputStream::Impl::ReportError() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  // TODO(miu): Need clean-up of AudioInputCallback interface in a future
+  // change, since its only implementation ignores the first argument entirely
+  // and the values for the second argument are undefined.
+  callback_->OnError(NULL, 0);
+}
+
+void WebContentsAudioInputStream::Impl::StartMirroring() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&AudioMirroringManager::StartMirroring,
+                 base::Unretained(mirroring_manager_),
+                 target_render_process_id_, target_render_view_id_,
+                 make_scoped_refptr(this)));
+}
+
+void WebContentsAudioInputStream::Impl::StopMirroring() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&AudioMirroringManager::StopMirroring,
+                 base::Unretained(mirroring_manager_),
+                 target_render_process_id_, target_render_view_id_,
+                 make_scoped_refptr(this)));
+}
+
+media::AudioOutputStream* WebContentsAudioInputStream::Impl::AddInput(
+    const media::AudioParameters& params) {
+  // Note: The closure created here holds a reference to "this," which will
+  // guarantee the VirtualAudioInputStream (mixer_stream_) outlives the
+  // VirtualAudioOutputStream.
+  return new media::VirtualAudioOutputStream(
+      params, message_loop_, mixer_stream_.get(),
+      base::Bind(&Impl::ReleaseInput, this));
+}
+
+void WebContentsAudioInputStream::Impl::ReleaseInput(
+    media::VirtualAudioOutputStream* stream) {
+  delete stream;
+}
+
+void WebContentsAudioInputStream::Impl::OnTargetChanged(int render_process_id,
+                                                        int render_view_id) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  if (target_render_process_id_ == render_process_id &&
+      target_render_view_id_ == render_view_id) {
+    return;
+  }
+
+  DVLOG(1) << "Target RenderView has changed from "
+           << target_render_process_id_ << ':' << target_render_view_id_
+           << " to " << render_process_id << ':' << render_view_id;
+
+  if (state_ == MIRRORING)
+    StopMirroring();
+
+  target_render_process_id_ = render_process_id;
+  target_render_view_id_ = render_view_id;
+
+  if (state_ == MIRRORING) {
+    if (IsTargetLost()) {
+      ReportError();
+      Stop();
+    } else {
+      StartMirroring();
+    }
+  }
+}
+
+// static
+WebContentsAudioInputStream* WebContentsAudioInputStream::Create(
+    const std::string& device_id,
+    const media::AudioParameters& params,
+    base::MessageLoopProxy* message_loop) {
+  int render_process_id;
+  int render_view_id;
+  if (!WebContentsCaptureUtil::ExtractTabCaptureTarget(
+          device_id, &render_process_id, &render_view_id)) {
+    return NULL;
+  }
+
+  return new WebContentsAudioInputStream(
+      render_process_id, render_view_id, message_loop,
+      BrowserMainLoop::GetAudioMirroringManager(),
+      new WebContentsTracker(),
+      new media::VirtualAudioInputStream(
+          params, message_loop,
+          media::VirtualAudioInputStream::AfterCloseCallback()));

[DaleCurtis, 2013/01/17 21:11:12]

This is a bit weird, you're binding in a callback to the class you're creating. 
Why not just do this internally?

[miu, 2013/01/17 22:44:12]

No, that's not what's going on here at all.  AfterCloseCallback is declared as:

  typedef base::Callback1<void(VirtualAudioInputStream*)> AfterCloseCallback;

All I'm doing here is calling the zero-arg Callback1 constructor, which
equivalent to binding a "do nothing" function.

This is why VAIS and VAOS originally had the separate RunOnceClosed() method. 
There are times (e.g., here and in unit tests) where we don't want VAIS to run
anything on Close().

+}
+
+WebContentsAudioInputStream::WebContentsAudioInputStream(
+    int render_process_id, int render_view_id,
+    base::MessageLoopProxy* message_loop,
+    AudioMirroringManager* mirroring_manager,
+    const scoped_refptr<WebContentsTracker>& tracker,
+    media::VirtualAudioInputStream* mixer_stream)
+    : impl_(new Impl(render_process_id, render_view_id, message_loop,
+                     mirroring_manager, tracker, mixer_stream)) {}
+
+WebContentsAudioInputStream::~WebContentsAudioInputStream() {}
+
+bool WebContentsAudioInputStream::Open() {
+  return impl_->Open();
+}
+
+void WebContentsAudioInputStream::Start(AudioInputCallback* callback) {
+  impl_->Start(callback);
+}
+
+void WebContentsAudioInputStream::Stop() {
+  impl_->Stop();
+}
+
+void WebContentsAudioInputStream::Close() {
+  impl_->Close();
+  delete this;
+}
+
+double WebContentsAudioInputStream::GetMaxVolume() {
+  return impl_->mixer_stream()->GetMaxVolume();
+}
+
+void WebContentsAudioInputStream::SetVolume(double volume) {
+  impl_->mixer_stream()->SetVolume(volume);
+}
+
+double WebContentsAudioInputStream::GetVolume() {
+  return impl_->mixer_stream()->GetVolume();
+}
+
+void WebContentsAudioInputStream::SetAutomaticGainControl(bool enabled) {
+  impl_->mixer_stream()->SetAutomaticGainControl(enabled);
+}
+
+bool WebContentsAudioInputStream::GetAutomaticGainControl() {
+  return impl_->mixer_stream()->GetAutomaticGainControl();
+}
+
+}  // namespace content