WebAudio: Fix AudioNode leak in a case that AudioNode is not disconnected from the graph explicitly.

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index a552cc3bcace888a7640d578698db16cd19550bd..0ae8284286368653772f4242475dd2bbe5d75e9d 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -918,6 +918,7 @@ void ThreadState::preGC()
     flushHeapDoesNotContainCacheIfNeeded();
     if (isMainThread())
         m_allocatedObjectSizeBeforeGC = Heap::allocatedObjectSize() + Heap::markedObjectSize();
+    invokePreMarkingTasks();
 }
 
 void ThreadState::postGC(GCType gcType)
@@ -942,11 +943,42 @@ void ThreadState::postGC(GCType gcType)
     }
 #endif
 
+    invokePostMarkingTasks();
     setGCState(gcType == GCWithSweep ? EagerSweepScheduled : LazySweepScheduled);
     for (int i = 0; i < NumberOfHeaps; i++)
         m_heaps[i]->prepareForSweep();
 }
 
+void ThreadState::invokePreMarkingTasks()
+{
+    ASSERT(isInGC());
+    for (MarkingTask* task : m_markingTasks)
+        task->willStartMarking(*this);
+}
+
+void ThreadState::invokePostMarkingTasks()
+{
+    ASSERT(isInGC());
+    for (size_t i = m_markingTasks.size(); i > 0; --i)
+        m_markingTasks[i - 1]->didFinishMarking(*this);
+}
+
+void ThreadState::addMarkingTask(MarkingTask* task)
+{
+    ASSERT(!isInGC());
+    checkThread();
+    m_markingTasks.append(task);
+}
+
+void ThreadState::removeMarkingTask(MarkingTask* task)
+{
+    ASSERT(!isInGC());
+    checkThread();
+    size_t position = m_markingTasks.find(task);
+    ASSERT(position != kNotFound);
+    m_markingTasks.remove(position);
+}
+
 void ThreadState::prepareHeapForTermination()
 {
     checkThread();
@@ -1101,6 +1133,19 @@ void ThreadState::postGCProcessing()
             }
         }
 
+        if (!m_zombies.isEmpty()) {
+            TRACE_EVENT0("blink_gc", "Heap::visitObjects");
+            // The following marking should not run in multiple threads because
+            // it uses global resources such as s_markingStack.
+            SafePointAwareMutexLocker locker(threadAttachMutex(), NoHeapPointersOnStack);
+            GCState originalState = gcState();
+            setGCState(GCRunning);
+            invokePreMarkingTasks();
+            Heap::visitObjects(this, m_zombies);
+            invokePostMarkingTasks();
+            setGCState(originalState);
+        }
+
         if (isMainThread())
             ScriptForbiddenScope::exit();
     }
@@ -1184,6 +1229,19 @@ void ThreadState::invokePreFinalizers(Visitor& visitor)
     m_preFinalizers.removeAll(deadObjects);
 }
 
+void ThreadState::markAsZombie(void* object)
+{
+    ASSERT(!isInGC());
+    checkThread();
+    ASSERT(!m_zombies.contains(object));
+    m_zombies.add(object);
+}
+
+void ThreadState::purifyZombies()
+{
+    m_zombies.clear();
+}
+
 #if ENABLE(GC_PROFILING)
 const GCInfo* ThreadState::findGCInfoFromAllThreads(Address address)
 {