Use ThreadScheduler::Current() in platform/.

This CL replaces the occurrences of "Platform::Current()
->CurrentThread()->Scheduler()" with "ThreadScheduler::Current()"
which has the same meaning.

Also, this CL simplifies the code that assumes Platform::CurrentThread()
or Thread::Scheduler() can return null, which is no longer true.

Bug: 826203
Change-Id: I0a59ef17be978d3a4d8b229dc19069aeb0a4c2f1
Reviewed-on: https://chromium-review.googlesource.com/c/1314084Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Yuta Kitamura <yutak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605275}

third_party/blink/renderer/platform/bindings/script_wrappable_marking_visitor.cc

@@ -98,16 +98,10 @@ void ScriptWrappableMarkingVisitor::PerformCleanup() {
 }
 
 void ScriptWrappableMarkingVisitor::ScheduleIdleLazyCleanup() {
-  Thread* const thread = Platform::Current()->CurrentThread();
-  // Thread might already be gone, or some threads (e.g. PPAPI) don't have a
-  // scheduler.
-  if (!thread || !thread->Scheduler())
-    return;
-
   if (idle_cleanup_task_scheduled_)
     return;
 
-  Platform::Current()->CurrentThread()->Scheduler()->PostIdleTask(
+  ThreadScheduler::Current()->PostIdleTask(
       FROM_HERE, WTF::Bind(&ScriptWrappableMarkingVisitor::PerformLazyCleanup,
                            WTF::Unretained(this)));
   idle_cleanup_task_scheduled_ = true;

third_party/blink/renderer/platform/graphics/begin_frame_provider.cc

@@ -62,10 +62,8 @@ void BeginFrameProvider::CreateCompositorFrameSinkIfNeeded() {
   Platform::Current()->GetInterfaceProvider()->GetInterface(
       mojo::MakeRequest(&provider));
 
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner;
-  auto* scheduler = blink::Platform::Current()->CurrentThread()->Scheduler();
-  if (scheduler)
-    task_runner = scheduler->CompositorTaskRunner();
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner =
+      ThreadScheduler::Current()->CompositorTaskRunner();
 
   mojom::blink::EmbeddedFrameSinkClientPtr efs_client;
   efs_binding_.Bind(mojo::MakeRequest(&efs_client), task_runner);

third_party/blink/renderer/platform/graphics/canvas_2d_layer_bridge.cc

@@ -415,7 +415,7 @@ void Canvas2DLayerBridge::SetIsHidden(bool hidden) {
           FROM_HERE, WTF::Bind(&HibernateWrapperForTesting,
                                weak_ptr_factory_.GetWeakPtr()));
     } else {
-      Platform::Current()->CurrentThread()->Scheduler()->PostIdleTask(
+      ThreadScheduler::Current()->PostIdleTask(
           FROM_HERE,
           WTF::Bind(&HibernateWrapper, weak_ptr_factory_.GetWeakPtr()));
     }

third_party/blink/renderer/platform/heap/thread_state.cc

@@ -221,15 +221,7 @@ void ThreadState::AttachMainThread() {
   thread_specific_ = new WTF::ThreadSpecific<ThreadState*>();
   new (main_thread_state_storage_) ThreadState();
 
-  // PpapiThread doesn't set the current thread.
-  Thread* current_thread = Platform::Current()->CurrentThread();
-  if (current_thread) {
-    ThreadScheduler* scheduler = current_thread->Scheduler();
-    // Some binaries do not have a scheduler (e.g.
-    // v8_context_snapshot_generator)
-    if (scheduler)
-      scheduler->AddRAILModeObserver(MainThreadState());
-  }
+  ThreadScheduler::Current()->AddRAILModeObserver(MainThreadState());
 }
 
 void ThreadState::AttachCurrentThread() {
@@ -693,7 +685,6 @@ ThreadState* ThreadState::FromObject(const void* object) {
 
 void ThreadState::PerformIdleGC(TimeTicks deadline) {
   DCHECK(CheckThread());
-  DCHECK(Platform::Current()->CurrentThread()->Scheduler());
 
   if (GetGCState() != kIdleGCScheduled)
     return;
@@ -707,10 +698,7 @@ void ThreadState::PerformIdleGC(TimeTicks deadline) {
   TimeDelta estimated_marking_time =
       heap_->stats_collector()->estimated_marking_time();
   if ((deadline - CurrentTimeTicks()) <= estimated_marking_time &&
-      !Platform::Current()
-           ->CurrentThread()
-           ->Scheduler()
-           ->CanExceedIdleDeadlineIfRequired()) {
+      !ThreadScheduler::Current()->CanExceedIdleDeadlineIfRequired()) {
     // If marking is estimated to take longer than the deadline and we can't
     // exceed the deadline, then reschedule for the next idle period.
     RescheduleIdleGC();
@@ -773,18 +761,13 @@ void ThreadState::ScheduleIncrementalMarkingFinalize() {
 }
 
 void ThreadState::ScheduleIdleGC() {
-  // Some threads (e.g. PPAPI thread) don't have a scheduler.
-  // Also some tests can call Platform::SetCurrentPlatformForTesting() at any
-  // time, so we need to check if it exists.
-  if (!Platform::Current()->CurrentThread()->Scheduler())
-    return;
   // Idle GC has the lowest priority so do not schedule if a GC is already
   // scheduled or if marking is in progress.
   if (GetGCState() != kNoGCScheduled)
     return;
   CompleteSweep();
   SetGCState(kIdleGCScheduled);
-  Platform::Current()->CurrentThread()->Scheduler()->PostNonNestableIdleTask(
+  ThreadScheduler::Current()->PostNonNestableIdleTask(
       FROM_HERE, WTF::Bind(&ThreadState::PerformIdleGC, WTF::Unretained(this)));
 }
 
@@ -795,11 +778,7 @@ void ThreadState::RescheduleIdleGC() {
 }
 
 void ThreadState::ScheduleIdleLazySweep() {
-  // Some threads (e.g. PPAPI thread) don't have a scheduler.
-  if (!Platform::Current()->CurrentThread()->Scheduler())
-    return;
-
-  Platform::Current()->CurrentThread()->Scheduler()->PostIdleTask(
+  ThreadScheduler::Current()->PostIdleTask(
       FROM_HERE,
       WTF::Bind(&ThreadState::PerformIdleLazySweep, WTF::Unretained(this)));
 }

third_party/blink/renderer/platform/scheduler/public/thread_scheduler.h

@@ -28,9 +28,6 @@ class PLATFORM_EXPORT ThreadScheduler {
       scheduler::WebThreadScheduler::RendererPauseHandle;
 
   // Return the current thread's ThreadScheduler.
-  //
-  // TODO(yutak): Replace all the "Platform::Current()->CurrentThread()
-  // ->Scheduler()" calls in Blink with this.
   static ThreadScheduler* Current();
 
   virtual ~ThreadScheduler() = default;

third_party/blink/renderer/platform/timer.cc

@@ -163,10 +163,8 @@ bool TimerBase::Comparator::operator()(const TimerBase* a,
 
 // static
 TimeTicks TimerBase::TimerCurrentTimeTicks() const {
-  return WTF::TimeTicks(Platform::Current()
-                            ->CurrentThread()
-                            ->Scheduler()
-                            ->MonotonicallyIncreasingVirtualTime());
+  return WTF::TimeTicks(
+      ThreadScheduler::Current()->MonotonicallyIncreasingVirtualTime());
 }
 
 }  // namespace blink