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

content/browser/renderer_host/media/web_contents_audio_input_stream.cc

Index: content/browser/renderer_host/media/web_contents_audio_input_stream.cc
diff --git a/content/browser/renderer_host/media/web_contents_audio_input_stream.cc b/content/browser/renderer_host/media/web_contents_audio_input_stream.cc
new file mode 100644
index 0000000000000000000000000000000000000000..64ebf47484d5bc10afe8b7333cc2a097e7c138d5
--- /dev/null
+++ b/content/browser/renderer_host/media/web_contents_audio_input_stream.cc
@@ -0,0 +1,166 @@
+// 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/web_contents_audio_input_stream.h"
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "content/browser/renderer_host/media/audio_renderer_host.h"
+#include "media/base/bind_to_loop.h"
+
+namespace content {
+
+//static
+WebContentsAudioInputStream* WebContentsAudioInputStream::Create(
+    const std::string& device_id) {
+  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);
+}
+
+WebContentsAudioInputStream::WebContentsAudioInputStream(int render_process_id,
+                                                         int render_view_id)
+    : state_(kConstructed),
+      target_render_process_id_(render_process_id),
+      target_render_view_id_(render_view_id) {
+}
+
+WebContentsAudioInputStream::~WebContentsAudioInputStream() {
+  DCHECK(!tracker_) << "BUG: Close() not called after Open().";
+}
+
+bool WebContentsAudioInputStream::Open() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (state_ != kConstructed) {
+    return false;
+  }
+
+  state_ = kOpened;
+
+  DCHECK(!tracker_);
+  tracker_ = new WebContentsCaptureUtil::RenderViewTracker();
+  tracker_->Start(
+      target_render_process_id_, target_render_view_id_,
+      media::BindToLoop(
+          base::MessageLoopProxy::current(),
+          base::Bind(&WebContentsAudioInputStream::OnTargetChanged, this)));
+
+  return true;
+}
+
+void WebContentsAudioInputStream::Start(AudioInputCallback* callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (state_ != kOpened) {
+    return;
+  }
+
+  state_ = kRecording;
+
+  if (target_host_) {
+    target_host_->StartMirroring(target_render_view_id_, this);

[Alpha Left Google, 2012/11/26 22:59:59]

Does it work if WCAIS doesn't own or reference ARH?

What if this becomes AudioRendererHost::StartMirroring(target_render_view_id,
this)?

[miu, 2012/11/28 05:05:01]

Done.

+  }
+}
+
+void WebContentsAudioInputStream::Stop() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (state_ != kRecording) {
+    return;
+  }
+
+  if (target_host_) {
+    target_host_->StopMirroring(target_render_view_id_, this);

[Alpha Left Google, 2012/11/26 22:59:59]

What if this becomes AudioRendererHost::StopMirroring(target_render_view_id)?

[miu, 2012/11/28 05:05:01]

Done.

+  }
+
+  state_ = kOpened;
+}
+
+void WebContentsAudioInputStream::Close() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  Stop();
+
+  target_host_ = NULL;
+  tracker_->Stop();
+  tracker_ = NULL;
+
+  state_ = kClosed;
+}
+
+void WebContentsAudioInputStream::OnTargetChanged(int render_process_id,
+                                                  int render_view_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (target_render_process_id_ == render_process_id &&
+      target_render_view_id_ == render_view_id) {
+    return;
+  }
+
+  if (state_ == kRecording) {
+    if (target_host_) {
+      target_host_->StopMirroring(target_render_view_id_, this);
+    }
+  }
+
+  target_render_process_id_ = render_process_id;
+  target_render_view_id_ = render_view_id;
+  target_host_ = AudioRendererHost::FromRenderProcessID(render_process_id);
+
+  if (state_ == kRecording) {
+    if (target_host_) {
+      target_host_->StartMirroring(target_render_view_id_, this);
+    }
+  }
+}
+
+double WebContentsAudioInputStream::GetMaxVolume() {
+  return 1.0;
+}
+
+void WebContentsAudioInputStream::SetVolume(double volume) {
+  // no-op
+}
+
+double WebContentsAudioInputStream::GetVolume() {
+  return 1.0;
+}
+
+void WebContentsAudioInputStream::SetAutomaticGainControl(bool enabled) {
+  // no-op
+}
+
+bool WebContentsAudioInputStream::GetAutomaticGainControl() {
+  return false;
+}
+
+void WebContentsAudioInputStream::AddAudioOutputStream(
+    media::DivertedAudioOutputStream* aos) {
+  base::AutoLock guard(streams_lock_);

[Alpha Left Google, 2012/11/26 22:59:59]

Is a lock necessary here? I see these two methods only called on IO thread.

[miu, 2012/11/28 05:05:01]

Removed the locking for now.  I agree that it'll probably turn out not to be
necessary when I replace the stubs in later CLs.

+  DCHECK(!streams_.count(aos)) << "BUG: Adding same stream twice.";
+  streams_.insert(aos);
+
+  DVLOG(1) << "STUB: WebContentsAudioInputStream@" << this
+           << "->AddAudioOutputStream(" << aos << ')';
+}
+
+void WebContentsAudioInputStream::RemoveAudioOutputStream(
+    media::DivertedAudioOutputStream* aos) {
+  base::AutoLock guard(streams_lock_);
+  DCHECK(streams_.count(aos)) << "BUG: Removing unknown stream.";
+  streams_.erase(aos);
+
+  DVLOG(1) << "STUB: WebContentsAudioInputStream@" << this
+           << "->RemoveAudioOutputStream(" << aos << ')';
+}
+
+}  // namespace content