Migrate AudioContext to use GC mojo wrappers.

No behavior change. This CL reduces potential risks of use-after-free bugs.

Bug: 1049056
Change-Id: Ia1031c5480e0b3aaf02371befc796db1166a6d2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2136012
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756926}

third_party/blink/renderer/modules/webaudio/audio_context.cc

@@ -131,6 +131,7 @@ AudioContext::AudioContext(Document& document,
                            base::Optional<float> sample_rate)
     : BaseAudioContext(&document, kRealtimeContext),
       context_id_(g_context_id++),
+      audio_context_manager_(document.ToExecutionContext()),
       keep_alive_(PERSISTENT_FROM_HERE, this) {
   destination_node_ =
       RealtimeAudioDestinationNode::Create(this, latency_hint, sample_rate);
@@ -168,7 +169,6 @@ AudioContext::AudioContext(Document& document,
           destination()->GetAudioDestinationHandler());
   base_latency_ = destination_handler.GetFramesPerBuffer() /
                   static_cast<double>(sampleRate());
-
 }
 
 void AudioContext::Uninitialize() {
@@ -196,6 +196,7 @@ AudioContext::~AudioContext() {
 
 void AudioContext::Trace(Visitor* visitor) {
   visitor->Trace(close_resolver_);
+  visitor->Trace(audio_context_manager_);
   BaseAudioContext::Trace(visitor);
 }
 
@@ -606,7 +607,7 @@ void AudioContext::NotifyAudibleAudioStarted() {
   DCHECK(IsMainThread());
 
   EnsureAudioContextManagerService();
-  if (audio_context_manager_)
+  if (audio_context_manager_.is_bound())
     audio_context_manager_->AudioContextAudiblePlaybackStarted(context_id_);
 }
 
@@ -697,17 +698,18 @@ void AudioContext::NotifyAudibleAudioStopped() {
   DCHECK(IsMainThread());
 
   EnsureAudioContextManagerService();
-  if (audio_context_manager_)
+  if (audio_context_manager_.is_bound())
     audio_context_manager_->AudioContextAudiblePlaybackStopped(context_id_);
 }
 
 void AudioContext::EnsureAudioContextManagerService() {
-  if (audio_context_manager_ || !GetDocument())
+  if (audio_context_manager_.is_bound() || !GetDocument())
     return;
 
   GetDocument()->GetFrame()->GetBrowserInterfaceBroker().GetInterface(
       mojo::GenericPendingReceiver(
-          audio_context_manager_.BindNewPipeAndPassReceiver()));
+          audio_context_manager_.BindNewPipeAndPassReceiver(
+              GetDocument()->GetTaskRunner(TaskType::kInternalMedia))));
 
   audio_context_manager_.set_disconnect_handler(
       WTF::Bind(&AudioContext::OnAudioContextManagerServiceConnectionError,

third_party/blink/renderer/modules/webaudio/audio_context.h

@@ -5,7 +5,6 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_CONTEXT_H_
 #define THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_CONTEXT_H_
 
-#include "mojo/public/cpp/bindings/remote.h"
 #include "third_party/blink/public/mojom/webaudio/audio_context_manager.mojom-blink.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_promise.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_promise_resolver.h"
@@ -14,6 +13,8 @@
 #include "third_party/blink/renderer/modules/webaudio/base_audio_context.h"
 #include "third_party/blink/renderer/platform/heap/handle.h"
 #include "third_party/blink/renderer/platform/heap/self_keep_alive.h"
+#include "third_party/blink/renderer/platform/mojo/heap_mojo_remote.h"
+#include "third_party/blink/renderer/platform/mojo/heap_mojo_wrapper_mode.h"
 
 namespace blink {
 
@@ -192,7 +193,9 @@ class MODULES_EXPORT AudioContext : public BaseAudioContext {
   double base_latency_ = 0;
 
   // AudioContextManager for reporting audibility.
-  mojo::Remote<mojom::blink::AudioContextManager> audio_context_manager_;
+  HeapMojoRemote<mojom::blink::AudioContextManager,
+                 HeapMojoWrapperMode::kWithoutContextObserver>
+      audio_context_manager_;
 
   // Keeps track if the output of this destination was audible, before the
   // current rendering quantum.  Used for recording "playback" time.