Expose WebThread rendering only when AudioWorklet flag is enabled

third_party/WebKit/Source/platform/audio/AudioDestination.cpp

Index: third_party/WebKit/Source/platform/audio/AudioDestination.cpp
diff --git a/third_party/WebKit/Source/platform/audio/AudioDestination.cpp b/third_party/WebKit/Source/platform/audio/AudioDestination.cpp
index 39d569fd56ae9f8ab1156cca8e02ef89622fce06..35cee1312d161545c0c14f2c98c6537eaa723f46 100644
--- a/third_party/WebKit/Source/platform/audio/AudioDestination.cpp
+++ b/third_party/WebKit/Source/platform/audio/AudioDestination.cpp
@@ -31,6 +31,7 @@
 #include <memory>
 #include "platform/CrossThreadFunctional.h"
 #include "platform/Histogram.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/WebTaskRunner.h"
 #include "platform/audio/AudioUtilities.h"
 #include "platform/audio/PushPullFIFO.h"
@@ -76,7 +77,8 @@ AudioDestination::AudioDestination(AudioIOCallback& callback,
       render_bus_(AudioBus::Create(number_of_output_channels,
                                    AudioUtilities::kRenderQuantumFrames)),
       callback_(callback),
-      frames_elapsed_(0) {
+      frames_elapsed_(0),
+      is_audio_worklet_enabled(RuntimeEnabledFeatures::audioWorkletEnabled()) {
   // Create WebAudioDevice. blink::WebAudioDevice is designed to support the
   // local input (e.g. loopback from OS audio system), but Chromium's media
   // renderer does not support it currently. Thus, we use zero for the number
@@ -90,6 +92,9 @@ AudioDestination::AudioDestination(AudioIOCallback& callback,
   if (!CheckBufferSize()) {
     NOTREACHED();
   }
+
+  LOG(INFO) << "AudioDestination::IsAudioWorkletEnabled() = "
+            << IsAudioWorkletEnabled();
 }
 
 AudioDestination::~AudioDestination() {
@@ -104,8 +109,7 @@ void AudioDestination::Render(const WebVector<float*>& destination_data,
   TRACE_EVENT1("webaudio", "AudioDestination::Render",
                "callback_buffer_size", number_of_frames);
 
-  // This method is called by AudioDeviceThread.
-  DCHECK(!IsRenderingThread());
+  DCHECK(!IsMainThread());
 
   CHECK_EQ(destination_data.size(), number_of_output_channels_);
   CHECK_EQ(number_of_frames, callback_buffer_size_);
@@ -123,28 +127,32 @@ void AudioDestination::Render(const WebVector<float*>& destination_data,
 
   size_t frames_to_render = fifo_->Pull(output_bus_.Get(), number_of_frames);
 
-  // TODO(hongchan): this check might be redundant, so consider removing later.
-  if (frames_to_render != 0 && rendering_thread_) {
-    rendering_thread_->GetWebTaskRunner()->PostTask(
-        BLINK_FROM_HERE,
-        CrossThreadBind(&AudioDestination::RequestRenderOnWebThread,
-                        CrossThreadUnretained(this), number_of_frames,
-                        frames_to_render, delay, delay_timestamp,
-                        prior_frames_skipped));
+  // If AudioWorklet is enabled, use dual thread rendering.
+  if (IsAudioWorkletEnabled()) {
+    // TODO(hongchan): this check might be redundant, so consider removing
+    // later.
+    if (frames_to_render != 0 && rendering_thread_) {
+      rendering_thread_->GetWebTaskRunner()->PostTask(
+          BLINK_FROM_HERE,
+          CrossThreadBind(&AudioDestination::RequestRender,
+                          CrossThreadUnretained(this), number_of_frames,
+                          frames_to_render, delay, delay_timestamp,
+                          prior_frames_skipped));
+    }
+  } else {
+    RequestRender(number_of_frames, frames_to_render, delay, delay_timestamp,
+                  prior_frames_skipped);
   }
 }
 
-void AudioDestination::RequestRenderOnWebThread(size_t frames_requested,
-                                                size_t frames_to_render,
-                                                double delay,
-                                                double delay_timestamp,
-                                                size_t prior_frames_skipped) {
-  TRACE_EVENT1("webaudio", "AudioDestination::RequestRenderOnWebThread",
+void AudioDestination::RequestRender(size_t frames_requested,
+                                     size_t frames_to_render,
+                                     double delay,
+                                     double delay_timestamp,
+                                     size_t prior_frames_skipped) {
+  TRACE_EVENT1("webaudio", "AudioDestination::RequestRender",
                "frames_to_render", frames_to_render);
 
-  // This method is called by WebThread.
-  DCHECK(IsRenderingThread());
-
   frames_elapsed_ -= std::min(frames_elapsed_, prior_frames_skipped);
   AudioIOPosition output_position;
   output_position.position =
@@ -184,8 +192,12 @@ void AudioDestination::Start() {
   // Start the "audio device" after the rendering thread is ready.
   if (web_audio_device_ && !is_playing_) {
     TRACE_EVENT0("webaudio", "AudioDestination::Start");
-    rendering_thread_ =
-        Platform::Current()->CreateThread("WebAudio Rendering Thread");
+
+    if (IsAudioWorkletEnabled()) {
+      rendering_thread_ =
+          Platform::Current()->CreateThread("WebAudio Rendering Thread");
+    }
+
     web_audio_device_->Start();
     is_playing_ = true;
   }
@@ -199,7 +211,11 @@ void AudioDestination::Stop() {
   if (web_audio_device_ && is_playing_) {
     TRACE_EVENT0("webaudio", "AudioDestination::Stop");
     web_audio_device_->Stop();
-    rendering_thread_.reset();
+
+    if (IsAudioWorkletEnabled()) {
+      rendering_thread_.reset();
+    }
+
     is_playing_ = false;
   }
 }
@@ -254,9 +270,4 @@ bool AudioDestination::CheckBufferSize() {
   return is_buffer_size_valid;
 }
 
-bool AudioDestination::IsRenderingThread() {
-  return static_cast<ThreadIdentifier>(rendering_thread_->ThreadId()) ==
-         CurrentThread();
-}
-
 }  // namespace blink