Use DEFINE_THREAD_SAFE_STATIC_LOCAL @WebAudioInputIPCFactory::get()

... as per section 2.1.2 in [1].

Method is also renamed to GetInstance().

[1] https://docs.google.com/document/d/19Zk6Fv1E-6QTQ2c33rpBjDNEkzlsSKvjb3hWkvZAE80

BUG=787252
R=guidou@chromim.org, haraken@chromium.org

Change-Id: I5a80ee2168d8b150439559ce74e9ce3fd6089b07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2391005
Commit-Queue: Antonio Gomes (GMT-4) <tonikitoo@igalia.com>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804551}

content/renderer/media/audio/audio_device_factory.cc

@@ -181,8 +181,8 @@ AudioDeviceFactory::NewAudioCapturerSource(
   }
 
   return base::MakeRefCounted<media::AudioInputDevice>(
-      blink::WebAudioInputIPCFactory::get()->CreateAudioInputIPC(frame_token,
-                                                                 params),
+      blink::WebAudioInputIPCFactory::GetInstance().CreateAudioInputIPC(
+          frame_token, params),
       media::AudioInputDevice::Purpose::kUserInput,
       media::AudioInputDevice::DeadStreamDetection::kEnabled);
 }

content/renderer/pepper/pepper_platform_audio_input.cc

@@ -173,7 +173,7 @@ void PepperPlatformAudioInput::InitializeOnIOThread(
   DCHECK(io_task_runner_->BelongsToCurrentThread());
 
   if (ipc_startup_state_ != kStopped)
-    ipc_ = blink::WebAudioInputIPCFactory::get()->CreateAudioInputIPC(
+    ipc_ = blink::WebAudioInputIPCFactory::GetInstance().CreateAudioInputIPC(
         render_frame_token_, media::AudioSourceParameters(session_id));
   if (!ipc_)
     return;

content/renderer/render_thread_impl.cc

@@ -625,8 +625,6 @@ void RenderThreadImpl::Init() {
   unfreezable_message_filter_ = new UnfreezableMessageFilter(this);
   AddFilter(unfreezable_message_filter_.get());
 
-  audio_input_ipc_factory_.emplace(main_thread_runner(), GetIOTaskRunner());
-
   audio_output_ipc_factory_.emplace(GetIOTaskRunner());
 
   GetContentClient()->renderer()->RenderThreadStarted();

content/renderer/render_thread_impl.h

@@ -61,7 +61,6 @@
 #include "third_party/blink/public/platform/scheduler/web_rail_mode_observer.h"
 #include "third_party/blink/public/platform/scheduler/web_thread_scheduler.h"
 #include "third_party/blink/public/platform/web_connection_type.h"
-#include "third_party/blink/public/web/modules/media/audio/web_audio_input_ipc_factory.h"
 #include "third_party/blink/public/web/modules/media/audio/web_audio_output_ipc_factory.h"
 #include "third_party/blink/public/web/web_memory_statistics.h"
 #include "ui/gfx/native_widget_types.h"
@@ -531,9 +530,6 @@ class CONTENT_EXPORT RenderThreadImpl
   // Filter out unfreezable messages and pass it to unfreezable task runners.
   scoped_refptr<UnfreezableMessageFilter> unfreezable_message_filter_;
 
-  // Provides AudioInputIPC objects for audio input devices. Initialized in
-  // Init.
-  base::Optional<blink::WebAudioInputIPCFactory> audio_input_ipc_factory_;
   // Provides AudioOutputIPC objects for audio output devices. Initialized in
   // Init.
   base::Optional<blink::WebAudioOutputIPCFactory> audio_output_ipc_factory_;

third_party/blink/public/web/modules/media/audio/web_audio_input_ipc_factory.h

@@ -29,13 +29,9 @@ class BLINK_MODULES_EXPORT WebAudioInputIPCFactory {
   WebAudioInputIPCFactory(
       scoped_refptr<base::SequencedTaskRunner> main_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> io_task_runner);
-
   ~WebAudioInputIPCFactory();
 
-  static WebAudioInputIPCFactory* get() {
-    DCHECK(instance_);
-    return instance_;
-  }
+  static WebAudioInputIPCFactory& GetInstance();
 
   const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner() const {
     return io_task_runner_;
@@ -50,9 +46,6 @@ class BLINK_MODULES_EXPORT WebAudioInputIPCFactory {
   const scoped_refptr<base::SequencedTaskRunner> main_task_runner_;
   const scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
-  // Global instance, set in constructor and unset in destructor.
-  static WebAudioInputIPCFactory* instance_;
-
   DISALLOW_COPY_AND_ASSIGN(WebAudioInputIPCFactory);
 };
 

third_party/blink/renderer/modules/media/audio/web_audio_input_ipc_factory.cc

@@ -15,9 +15,12 @@
 #include "mojo/public/cpp/bindings/pending_receiver.h"
 #include "mojo/public/cpp/bindings/pending_remote.h"
 #include "third_party/blink/public/mojom/media/renderer_audio_input_stream_factory.mojom-blink.h"
+#include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/public/web/web_local_frame.h"
 #include "third_party/blink/public/web/web_local_frame_client.h"
 #include "third_party/blink/renderer/modules/media/audio/mojo_audio_input_ipc.h"
+#include "third_party/blink/renderer/platform/scheduler/public/thread.h"
+#include "third_party/blink/renderer/platform/wtf/std_lib_extras.h"
 
 namespace blink {
 
@@ -75,21 +78,20 @@ void AssociateInputAndOutputForAec(
 }
 }  // namespace
 
-WebAudioInputIPCFactory* WebAudioInputIPCFactory::instance_ = nullptr;
+WebAudioInputIPCFactory& WebAudioInputIPCFactory::GetInstance() {
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(WebAudioInputIPCFactory, instance,
+                                  (Thread::MainThread()->GetTaskRunner(),
+                                   Platform::Current()->GetIOTaskRunner()));
+  return instance;
+}
 
 WebAudioInputIPCFactory::WebAudioInputIPCFactory(
     scoped_refptr<base::SequencedTaskRunner> main_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
     : main_task_runner_(std::move(main_task_runner)),
-      io_task_runner_(std::move(io_task_runner)) {
-  DCHECK(!instance_);
-  instance_ = this;
-}
+      io_task_runner_(std::move(io_task_runner)) {}
 
-WebAudioInputIPCFactory::~WebAudioInputIPCFactory() {
-  DCHECK_EQ(instance_, this);
-  instance_ = nullptr;
-}
+WebAudioInputIPCFactory::~WebAudioInputIPCFactory() = default;
 
 std::unique_ptr<media::AudioInputIPC>
 WebAudioInputIPCFactory::CreateAudioInputIPC(