Tab Audio Capture: Browser-side connect/disconnect functionality.

content/browser/renderer_host/media/audio_renderer_host.cc

 // Copyright (c) 2012 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/audio_renderer_host.h"
 
 #include "base/bind.h"
+#include "base/lazy_instance.h"
 #include "base/metrics/histogram.h"
 #include "base/process.h"
 #include "base/shared_memory.h"
 #include "content/browser/browser_main_loop.h"
 #include "content/browser/renderer_host/media/audio_sync_reader.h"
+#include "content/browser/renderer_host/media/web_contents_audio_input_stream.h"
 #include "content/common/media/audio_messages.h"
 #include "content/public/browser/media_observer.h"
+#include "media/audio/audio_io.h"
 #include "media/audio/shared_memory_util.h"
 #include "media/base/audio_bus.h"
 #include "media/base/limits.h"
 
 using media::AudioBus;
 
 namespace content {
 
 struct AudioRendererHost::AudioEntry {
   AudioEntry();
   ~AudioEntry();
 
   // The AudioOutputController that manages the audio stream.
   scoped_refptr<media::AudioOutputController> controller;
 
   // The audio stream ID.
   int stream_id;
 
+  // The routing ID of the source render view.
+  int render_view_id;
+
   // Shared memory for transmission of the audio data.
   base::SharedMemory shared_memory;
 
   // The synchronous reader to be used by the controller. We have the
   // ownership of the reader.
   scoped_ptr<media::AudioOutputController::SyncReader> reader;
 
+  // When non-NULL, normal audio output is being diverted for audio mirroring.
+  scoped_ptr<media::DivertedAudioOutputStream> diverted_stream;

[Alpha Left Google, 2012/11/20 21:49:43]

Should this be owned by AudioOutputController instead?

+
   // Set to true after we called Close() for the controller.
   bool pending_close;
 };
 
 AudioRendererHost::AudioEntry::AudioEntry()
     : stream_id(0),
+      render_view_id(MSG_ROUTING_NONE),
       pending_close(false) {
 }
 
 AudioRendererHost::AudioEntry::~AudioEntry() {}
 
+namespace {
+
+struct GlobalLookup {
+  base::Lock lock;

[Alpha Left Google, 2012/11/20 21:49:43]

I don't think a lock is necessary, rather ASSERT for threads.

[miu, 2012/11/21 08:27:48]

Unfortunately, the lock will be needed since an entry is added/removed from the
map via the UI BrowserThread (whenever a RenderProcessHost is
created/destroyed), but the map is read via the IO thread.

Do you know of a better way to look-up the AudioRendererHost instance by
render_process_id?

+  std::map<int, AudioRendererHost*> by_process_id;
+};
+
+base::LazyInstance<GlobalLookup>::Leaky g_lookup = LAZY_INSTANCE_INITIALIZER;
+
+void RegisterAudioRendererHost(int render_process_id, AudioRendererHost* arh) {
+  GlobalLookup& lookup = g_lookup.Get();
+  base::AutoLock guard(lookup.lock);
+  lookup.by_process_id.insert(std::make_pair(render_process_id, arh));
+}
+
+void DeregisterAudioRendererHost(int render_process_id) {
+  GlobalLookup& lookup = g_lookup.Get();
+  base::AutoLock guard(lookup.lock);
+  lookup.by_process_id.erase(render_process_id);
+}
+
+}  // namespace
+
+// static
+scoped_refptr<AudioRendererHost> AudioRendererHost::FromRenderProcessID(
+    int render_process_id) {
+  GlobalLookup& lookup = g_lookup.Get();

[Alpha Left Google, 2012/11/20 21:49:43]

Assert for threads.

+  base::AutoLock guard(lookup.lock);
+  std::map<int, AudioRendererHost*>::const_iterator it =
+      lookup.by_process_id.find(render_process_id);
+  return (it != lookup.by_process_id.end()) ? it->second : NULL;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // AudioRendererHost implementations.
 AudioRendererHost::AudioRendererHost(
+    int render_process_id,
     media::AudioManager* audio_manager, MediaObserver* media_observer)
-    : audio_manager_(audio_manager),
+    : render_process_id_(render_process_id),
+      audio_manager_(audio_manager),
       media_observer_(media_observer) {
+  RegisterAudioRendererHost(render_process_id_, this);
 }
 
 AudioRendererHost::~AudioRendererHost() {
   DCHECK(audio_entries_.empty());
+  DCHECK(mirror_sessions_.empty());
+  DeregisterAudioRendererHost(render_process_id_);

[Alpha Left Google, 2012/11/20 21:49:43]

How does each |destination| know when to call StopMirroring() when this is being
destroyed.

[miu, 2012/11/21 08:27:48]

AudioRendererHost is ref-counted.  Each |destination| holds a ref to
AudioRendererHost until StopMirroring() is called, so it's guaranteed not to go
away.

 }
 
 void AudioRendererHost::OnChannelClosing() {
   BrowserMessageFilter::OnChannelClosing();
 
   // Since the IPC channel is gone, close all requested audio streams.
   DeleteEntries();
 }
 
 void AudioRendererHost::OnDestruct() const {
@@ skipping 136 matching lines @@
     IPC_MESSAGE_HANDLER(AudioHostMsg_PauseStream, OnPauseStream)
     IPC_MESSAGE_HANDLER(AudioHostMsg_FlushStream, OnFlushStream)
     IPC_MESSAGE_HANDLER(AudioHostMsg_CloseStream, OnCloseStream)
     IPC_MESSAGE_HANDLER(AudioHostMsg_SetVolume, OnSetVolume)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP_EX()
 
   return handled;
 }
 
+void AudioRendererHost::StartMirroring(
+    int render_view_id, WebContentsAudioInputStream* destination) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(destination);
+
+  MirrorSessionMap::iterator session_it = mirror_sessions_.find(render_view_id);
+  if (session_it != mirror_sessions_.end()) {
+    DVLOG(1) << "Forcing StopMirroring(" << render_view_id
+             << ") on existing mirroring session (@" << session_it->second
+             << ").";
+    StopMirroring(render_view_id, session_it->second);

[Alpha Left Google, 2012/11/20 21:49:43]

Should this just be an error?

[miu, 2012/11/21 08:27:48]

Justin and I talked about this.  He believe the extension API should enforce the
"one mirroring of a tab at a time" constraint.  I've put this here as a
precaution for now and it really doesn't hurt anything to leave it in (an extra
protection).

+  }
+
+  DVLOG(1) << "StartMirroring RenderView " << render_view_id
+           << " --> WebContentsAudioInputStream@" << destination;
+
+  mirror_sessions_.insert(std::make_pair(render_view_id, destination));
+  for (AudioEntryMap::const_iterator it = audio_entries_.begin();
+       it != audio_entries_.end(); ++it) {
+    if (it->second->render_view_id == render_view_id) {
+      it->second->diverted_stream.reset(it->second->controller->Divert());
+      destination->AddAudioOutputStream(it->second->diverted_stream.get());
+    }
+  }
+}
+
+void AudioRendererHost::StopMirroring(
+    int render_view_id, WebContentsAudioInputStream* destination) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  MirrorSessionMap::iterator session_it = mirror_sessions_.find(render_view_id);
+  if (session_it == mirror_sessions_.end() ||
+      destination != session_it->second) {
+    return;
+  }
+
+  DVLOG(1) << "StopMirroring RenderView " << render_view_id
+           << " --> WebContentsAudioInputStream@" << destination;
+
+  for (AudioEntryMap::const_iterator it = audio_entries_.begin();
+       it != audio_entries_.end(); ++it) {
+    if (it->second->render_view_id == render_view_id) {
+      destination->RemoveAudioOutputStream(it->second->diverted_stream.get());
+      it->second->diverted_stream.reset();
+    }
+  }
+  mirror_sessions_.erase(session_it);
+}
+
 void AudioRendererHost::OnCreateStream(
     int stream_id, const media::AudioParameters& params, int input_channels) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK(LookupById(stream_id) == NULL);
 
   media::AudioParameters audio_params(params);
   uint32 buffer_size = media::AudioBus::CalculateMemorySize(audio_params);
   DCHECK_GT(buffer_size, 0U);
   DCHECK_LE(buffer_size,
             static_cast<uint32>(media::limits::kMaxPacketSizeInBytes));
@@ skipping 47 matching lines @@
   }
 
   // If we have created the controller successfully, create an entry and add it
   // to the map.
   entry->stream_id = stream_id;
   audio_entries_.insert(std::make_pair(stream_id, entry.release()));
   if (media_observer_)
     media_observer_->OnSetAudioStreamStatus(this, stream_id, "created");
 }
 
+void AudioRendererHost::OnAssociateStreamWithProducer(int stream_id,
+                                                      int render_view_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  AudioEntry* const entry = LookupById(stream_id);
+  if (!entry) {
+    SendErrorMessage(stream_id);
+    return;
+  }
+
+  if (entry->render_view_id == render_view_id)
+    return;  // No change.
+
+  MirrorSessionMap::const_iterator prev_session_it =

[Alpha Left Google, 2012/11/20 21:49:43]

Comments to explain what this is doing.

[miu, 2012/11/21 08:27:48]

Done.

+      mirror_sessions_.find(entry->render_view_id);
+  scoped_ptr<media::DivertedAudioOutputStream> diverted_stream;
+  if (prev_session_it != mirror_sessions_.end()) {
+    prev_session_it->second->
+        RemoveAudioOutputStream(entry->diverted_stream.get());
+    diverted_stream.swap(entry->diverted_stream);
+  }
+
+  entry->render_view_id = render_view_id;
+
+  MirrorSessionMap::const_iterator next_session_it =

[Alpha Left Google, 2012/11/20 21:49:43]

Would be helpful to explain what this is supposed to do.

[miu, 2012/11/21 08:27:48]

Done.

+      mirror_sessions_.find(render_view_id);
+  if (next_session_it != mirror_sessions_.end()) {
+    if (diverted_stream) {
+      entry->diverted_stream.swap(diverted_stream);
+    } else {
+      entry->diverted_stream.reset(entry->controller->Divert());
+    }
+    next_session_it->second->AddAudioOutputStream(entry->diverted_stream.get());
+  }
+}
+
 void AudioRendererHost::OnPlayStream(int stream_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   AudioEntry* entry = LookupById(stream_id);
   if (!entry) {
     SendErrorMessage(stream_id);
     return;
   }
 
   entry->controller->Play();
@@ skipping 69 matching lines @@
   for (AudioEntryMap::iterator i = audio_entries_.begin();
        i != audio_entries_.end(); ++i) {
     CloseAndDeleteStream(i->second);
   }
 }
 
 void AudioRendererHost::CloseAndDeleteStream(AudioEntry* entry) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   if (!entry->pending_close) {
+    MirrorSessionMap::const_iterator session_it =
+        mirror_sessions_.find(entry->render_view_id);
+    if (session_it != mirror_sessions_.end()) {
+      session_it->second->RemoveAudioOutputStream(entry->diverted_stream.get());
+      entry->diverted_stream.reset();
+    }
     entry->controller->Close(
         base::Bind(&AudioRendererHost::DeleteEntry, this, entry));
     entry->pending_close = true;
   }
 }
 
 void AudioRendererHost::DeleteEntry(AudioEntry* entry) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   // Delete the entry when this method goes out of scope.
@@ skipping 42 matching lines @@
   return NULL;
 }
 
 media::AudioOutputController* AudioRendererHost::LookupControllerByIdForTesting(
     int stream_id) {
   AudioEntry* const entry = LookupById(stream_id);
   return entry ? entry->controller : NULL;
 }
 
 }  // namespace content