Use enum for per thread heap enabled flag

third_party/WebKit/Source/platform/heap/ThreadState.h

Index: third_party/WebKit/Source/platform/heap/ThreadState.h
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.h b/third_party/WebKit/Source/platform/heap/ThreadState.h
index 76fae9b74356c94dbe553c19fc4fcb2f21703836..82bd79c4bed610bef30fc89440517f82578e3f6b 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.h
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.h
@@ -174,7 +174,7 @@ public:
     void lockThreadAttachMutex();
     void unlockThreadAttachMutex();
 
-    bool perThreadHeapEnabled() const { return m_perThreadHeapEnabled; }
+    BlinkGC::ThreadHeapMode threadHeapMode() const { return m_threadHeapMode; }
 
     bool isTerminating() { return m_isTerminating; }
 
@@ -185,7 +185,7 @@ public:
     // Associate ThreadState object with the current thread. After this
     // call thread can start using the garbage collected heap infrastructure.
     // It also has to periodically check for safepoints.
-    static void attachCurrentThread(bool perThreadHeapEnabled);
+    static void attachCurrentThread(BlinkGC::ThreadHeapMode);
 
     // Disassociate attached ThreadState from the current thread. The thread
     // can no longer use the garbage collected heap after this call.
@@ -540,7 +540,7 @@ private:
         FreelistSnapshot
     };
 
-    ThreadState(bool perThreadHeapEnabled);
+    explicit ThreadState(BlinkGC::ThreadHeapMode);
     ~ThreadState();
 
     NO_SANITIZE_ADDRESS void copyStackUntilSafePointScope();
@@ -650,7 +650,7 @@ private:
     size_t m_arenaAges[BlinkGC::NumberOfArenas];
     size_t m_currentArenaAges;
 
-    bool m_perThreadHeapEnabled;
+    const BlinkGC::ThreadHeapMode m_threadHeapMode;
     bool m_isTerminating;
     GarbageCollectedMixinConstructorMarker* m_gcMixinMarker;