Merge TaskSynchronizer into WaitableEvent.

third_party/WebKit/Source/platform/WaitableEvent.cpp

 // Copyright 2016 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 "platform/WaitableEvent.h"
 
 #include "base/synchronization/waitable_event.h"
+#include "platform/heap/SafePoint.h"
+#include "platform/heap/ThreadState.h"
+#include "wtf/Optional.h"
 #include "wtf/PtrUtil.h"
 #include <vector>
 
 namespace blink {
 
 WaitableEvent::WaitableEvent(ResetPolicy policy, InitialState state)
 {
     m_impl = wrapUnique(new base::WaitableEvent(
         policy == ResetPolicy::Manual
             ? base::WaitableEvent::ResetPolicy::MANUAL
             : base::WaitableEvent::ResetPolicy::AUTOMATIC,
         state == InitialState::Signaled
             ? base::WaitableEvent::InitialState::SIGNALED
             : base::WaitableEvent::InitialState::NOT_SIGNALED));
 }
 
 WaitableEvent::~WaitableEvent() {}
 
 void WaitableEvent::reset()
 {
     m_impl->Reset();
 }
 
 void WaitableEvent::wait()
 {
-    m_impl->Wait();
+    if (ThreadState::current()) {
+        // We only enter a safe point scope if the thread is attached, ex. never
+        // during shutdown.
+        // TODO(esprehn): Why can't SafePointScope do this for us?
+        SafePointScope scope(BlinkGC::HeapPointersOnStack);
+        m_impl->Wait();
+    } else {
+        m_impl->Wait();
+    }
 }
 
 void WaitableEvent::signal()
 {
     m_impl->Signal();
 }
 
 size_t WaitableEvent::waitMultiple(const WTF::Vector<WaitableEvent*>& events)
 {
     std::vector<base::WaitableEvent*> baseEvents;
     for (size_t i = 0; i < events.size(); ++i)
         baseEvents.push_back(events[i]->m_impl.get());
     size_t idx = base::WaitableEvent::WaitMany(baseEvents.data(), baseEvents.size());
     DCHECK_LT(idx, events.size());
     return idx;
 }
 
 } // namespace blink