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

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index 83b5f2510baaa405905af5e07c561e76283b9ade..6a1c2b6367e597b282ba4d7ba8e77c58e127897b 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -12,6 +12,7 @@
 #include "content/browser/renderer_host/media/audio_sync_reader.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"
@@ -30,6 +31,9 @@ struct AudioRendererHost::AudioEntry {
   // 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;
 
@@ -37,27 +41,48 @@ struct AudioRendererHost::AudioEntry {
   // ownership of the reader.
   scoped_ptr<media::AudioOutputController::SyncReader> reader;
 
+  // When non-NULL, normal audio output is being diverted for audio mirroring.
+  media::AudioOutputStream::AudioSourceCallback* diverted_callback;
+
   // 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),
+      diverted_callback(NULL),
       pending_close(false) {
 }
 
-AudioRendererHost::AudioEntry::~AudioEntry() {}
+AudioRendererHost::AudioEntry::~AudioEntry() {
+  DCHECK(!diverted_callback);
+}
+
+AudioRendererHost::MirroringDestination::~MirroringDestination() {}
 
 ///////////////////////////////////////////////////////////////////////////////
 // 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) {
 }
 
 AudioRendererHost::~AudioRendererHost() {
   DCHECK(audio_entries_.empty());
+  DCHECK(mirror_sessions_.empty());
+}
+
+base::LazyInstance<AudioRendererHost::ActiveHostMap>::Leaky
+    AudioRendererHost::g_host_map_ = LAZY_INSTANCE_INITIALIZER;
+
+void AudioRendererHost::OnChannelConnected(int32 peer_pid) {
+  g_host_map_.Get().insert(std::make_pair(render_process_id_, this));
+
+  BrowserMessageFilter::OnChannelConnected(peer_pid);
 }
 
 void AudioRendererHost::OnChannelClosing() {
@@ -65,6 +90,13 @@ void AudioRendererHost::OnChannelClosing() {
 
   // Since the IPC channel is gone, close all requested audio streams.
   DeleteEntries();
+
+  while (!mirror_sessions_.empty()) {
+    MirrorSessionMap::iterator it = mirror_sessions_.begin();
+    DoStopMirroring(render_process_id_, it->first, it->second);
+  }
+
+  g_host_map_.Get().erase(render_process_id_);
 }
 
 void AudioRendererHost::OnDestruct() const {
@@ -216,6 +248,146 @@ bool AudioRendererHost::OnMessageReceived(const IPC::Message& message,
   return handled;
 }
 
+// static
+AudioRendererHost* AudioRendererHost::FromRenderProcessID(
+    int render_process_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // Note: It's possible for look-ups to fail since, for example, an
+  // AudioRendererHost could be shutdown before StartMirroring() is called.
+  // It's common for mirroring sessions to target a different render
+  // process/view than the one that will receive the mirrored audio data.
+  // Example sequence of events:
+  //
+  //   1. RenderProcess_1 wants to mirror a tab within RenderProcess_2.
+  //   2. RenderProcess_1 starts sending IPCs to initiate a mirroring session.
+  //   3. In the meantime, RenderProcess_2 is shut down (e.g., tab closed).  The
+  //      AudioRendererHost for RenderProcess_2 is destroyed as a result.
+  //   4. A browser-side entity for RenderProcess_1 attempts to call
+  //      StartMirroring(), but since the AudioRendererHost for RenderProcess_2
+  //      is gone, the look-up here fails.
+
+  ActiveHostMap& host_map = g_host_map_.Get();
+  ActiveHostMap::const_iterator it = host_map.find(render_process_id);
+  return it == host_map.end() ? NULL : it->second;
+}
+
+// static
+void AudioRendererHost::StartMirroring(
+    int render_process_id, int render_view_id,
+    const scoped_refptr<MirroringDestination>& destination) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&AudioRendererHost::DoStartMirroring,
+                 render_process_id, render_view_id, destination));
+}
+
+// static
+void AudioRendererHost::DoStartMirroring(
+    int render_process_id, int render_view_id,
+    const scoped_refptr<MirroringDestination>& destination) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(destination);
+
+  AudioRendererHost* const host = FromRenderProcessID(render_process_id);
+  if (!host) {
+    return;  // See comment in FromRenderProcessID().
+  }
+
+  // Insert an entry into the set of active mirroring sessions.  If a mirroring
+  // session is already active for |render_process_id| + |render_view_id|,
+  // replace the entry.
+  MirrorSessionMap::iterator session_it =
+      host->mirror_sessions_.find(render_view_id);
+  scoped_refptr<MirroringDestination> old_destination;
+  if (session_it == host->mirror_sessions_.end()) {
+    host->mirror_sessions_.insert(std::make_pair(render_view_id, destination));
+
+    DVLOG(1) << "Start mirroring render_process_id:render_view_id="
+             << render_process_id << ':' << render_view_id
+             << " --> MirroringDestination@" << destination;
+  } else {
+    old_destination = session_it->second;
+    session_it->second = destination;
+
+    DVLOG(1) << "Switch mirroring of render_process_id:render_view_id="
+             << render_process_id << ':' << render_view_id
+             << "  MirroringDestination@" << old_destination
+             << " --> MirroringDestination@" << destination;
+  }
+
+  // Divert any existing audio outputs to |destination|.  If streams were
+  // already diverted to the |old_destination|, move them to the new
+  // |destination|.
+  for (AudioEntryMap::const_iterator it = host->audio_entries_.begin();
+       it != host->audio_entries_.end(); ++it) {
+    AudioEntry* const entry = it->second;
+    if (entry->render_view_id == render_view_id && !entry->pending_close) {
+      if (old_destination) {
+        DCHECK(entry->diverted_callback);
+        old_destination->RemoveInput(
+            entry->diverted_callback,
+            base::Bind(&MirroringDestination::AddInput, destination,
+                       entry->diverted_callback, entry->controller->params()));
+      } else {
+        DCHECK(!entry->diverted_callback);
+        entry->diverted_callback = entry->controller->Divert();
+        destination->AddInput(entry->diverted_callback,
+                              entry->controller->params());
+      }
+    }
+  }
+}
+
+// static
+void AudioRendererHost::StopMirroring(
+    int render_process_id, int render_view_id,
+    const scoped_refptr<MirroringDestination>& destination) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&AudioRendererHost::DoStopMirroring,
+                 render_process_id, render_view_id, destination));
+}
+
+// static
+void AudioRendererHost::DoStopMirroring(
+    int render_process_id, int render_view_id,
+    const scoped_refptr<MirroringDestination>& destination) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  AudioRendererHost* const host = FromRenderProcessID(render_process_id);
+  if (!host) {
+    return;  // See comment in FromRenderProcessID().
+  }
+
+  MirrorSessionMap::iterator session_it =
+      host->mirror_sessions_.find(render_view_id);
+  if (session_it == host->mirror_sessions_.end() ||
+      destination != session_it->second) {
+    return;
+  }
+
+  DVLOG(1) << "Stop mirroring render_process_id:render_view_id="
+           << render_process_id << ':' << render_view_id
+           << " --> MirroringDestination@" << destination;
+
+  // Revert the "divert" for each audio stream currently active in the mirroring
+  // session being stopped.
+  for (AudioEntryMap::const_iterator it = host->audio_entries_.begin();
+       it != host->audio_entries_.end(); ++it) {
+    AudioEntry* const entry = it->second;
+    if (entry->render_view_id == render_view_id && entry->diverted_callback) {
+      destination->RemoveInput(
+          entry->diverted_callback,
+          base::Bind(&media::AudioOutputController::Revert, entry->controller,
+                     entry->diverted_callback));
+      entry->diverted_callback = NULL;
+    }
+  }
+
+  host->mirror_sessions_.erase(session_it);
+}
+
 void AudioRendererHost::OnCreateStream(
     int stream_id, const media::AudioParameters& params, int input_channels) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
@@ -285,10 +457,48 @@ void AudioRendererHost::OnCreateStream(
 
 void AudioRendererHost::OnAssociateStreamWithProducer(int stream_id,
                                                       int render_view_id) {
-  // TODO(miu): Will use render_view_id in upcoming change.
-  DVLOG(1) << "AudioRendererHost@" << this
-           << "::OnAssociateStreamWithProducer(stream_id=" << stream_id
-           << ", render_view_id=" << 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 =
+      mirror_sessions_.find(entry->render_view_id);
+  entry->render_view_id = render_view_id;
+  MirrorSessionMap::const_iterator next_session_it =
+      mirror_sessions_.find(render_view_id);
+
+  // Determine whether this stream was already part of a mirroring session, and
+  // whether it should be participate in another mirroring session.
+  if (prev_session_it != mirror_sessions_.end() && entry->diverted_callback) {
+    if (next_session_it != mirror_sessions_.end() && !entry->pending_close) {
+      // Stream was part of a previous mirroring session, and needs to be
+      // transferred to a different one.
+      prev_session_it->second->RemoveInput(
+          entry->diverted_callback,
+          base::Bind(&MirroringDestination::AddInput, next_session_it->second,
+                     entry->diverted_callback, entry->controller->params()));
+    } else {
+      // Stream is no longer participating in a mirroring session.
+      prev_session_it->second->RemoveInput(
+          entry->diverted_callback,
+          base::Bind(&media::AudioOutputController::Revert, entry->controller,
+                     entry->diverted_callback));
+      entry->diverted_callback = NULL;
+    }
+  } else if (next_session_it != mirror_sessions_.end() &&
+             !entry->pending_close) {
+    // Stream wasn't before, but is now participating in a mirroring session.
+    entry->diverted_callback = entry->controller->Divert();
+    next_session_it->second->AddInput(entry->diverted_callback,
+                                      entry->controller->params());
+  }
 }
 
 void AudioRendererHost::OnPlayStream(int stream_id) {
@@ -380,8 +590,20 @@ void AudioRendererHost::CloseAndDeleteStream(AudioEntry* entry) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   if (!entry->pending_close) {
+    // If this stream is currently being mirrored, remove it from the mirroring
+    // session.
+    MirrorSessionMap::const_iterator session_it =
+        mirror_sessions_.find(entry->render_view_id);
+    if (session_it != mirror_sessions_.end() && entry->diverted_callback) {
+      session_it->second->RemoveInput(
+          entry->diverted_callback,
+          base::Bind(&media::AudioOutputController::Revert, entry->controller,
+                     entry->diverted_callback));
+    }
+
     entry->controller->Close(
         base::Bind(&AudioRendererHost::DeleteEntry, this, entry));
+    entry->diverted_callback = NULL;
     entry->pending_close = true;
   }
 }