Rename and improve "traceable" templates.

third_party/WebKit/Source/wtf/Vector.h

Index: third_party/WebKit/Source/wtf/Vector.h
diff --git a/third_party/WebKit/Source/wtf/Vector.h b/third_party/WebKit/Source/wtf/Vector.h
index 0dfcdab7d9370d7a93f3dff10cceb44bacd46098..9722d7eaf906fa9b3ba5615311f2c6ea71f8c43c 100644
--- a/third_party/WebKit/Source/wtf/Vector.h
+++ b/third_party/WebKit/Source/wtf/Vector.h
@@ -355,13 +355,13 @@ public:
         // If the vector backing is garbage-collected and needs tracing or
         // finalizing, we clear out the unused slots so that the visitor or the
         // finalizer does not cause a problem when visiting the unused slots.
-        VectorUnusedSlotClearer<Allocator::isGarbageCollected && (VectorTraits<T>::needsDestruction || NeedsTracingTrait<VectorTraits<T>>::value), T>::clear(from, to);
+        VectorUnusedSlotClearer<Allocator::isGarbageCollected && (VectorTraits<T>::needsDestruction || IsTraceableInCollectionTrait<VectorTraits<T>>::value), T>::clear(from, to);
     }
 
     void checkUnusedSlots(const T* from, const T* to)
     {
 #if ENABLE(ASSERT) && !defined(ANNOTATE_CONTIGUOUS_CONTAINER)
-        VectorUnusedSlotClearer<Allocator::isGarbageCollected && (VectorTraits<T>::needsDestruction || NeedsTracingTrait<VectorTraits<T>>::value), T>::checkCleared(from, to);
+        VectorUnusedSlotClearer<Allocator::isGarbageCollected && (VectorTraits<T>::needsDestruction || IsTraceableInCollectionTrait<VectorTraits<T>>::value), T>::checkCleared(from, to);
 #endif
     }
 
@@ -778,7 +778,7 @@ public:
     Vector()
     {
         static_assert(!std::is_polymorphic<T>::value || !VectorTraits<T>::canInitializeWithMemset, "Cannot initialize with memset if there is a vtable");
-        static_assert(Allocator::isGarbageCollected || !AllowsOnlyPlacementNew<T>::value || !NeedsTracing<T>::value, "Cannot put DISALLOW_NEW_EXCEPT_PLACEMENT_NEW objects that have trace methods into an off-heap Vector");
+        static_assert(Allocator::isGarbageCollected || !AllowsOnlyPlacementNew<T>::value || !IsTraceable<T>::value, "Cannot put DISALLOW_NEW_EXCEPT_PLACEMENT_NEW objects that have trace methods into an off-heap Vector");
         static_assert(Allocator::isGarbageCollected || !IsPointerToGarbageCollectedType<T>::value, "Cannot put raw pointers to garbage-collected classes into an off-heap Vector.  Use HeapVector<Member<T>> instead.");
 
         ANNOTATE_NEW_BUFFER(begin(), capacity(), 0);
@@ -789,7 +789,7 @@ public:
         : Base(size)
     {
         static_assert(!std::is_polymorphic<T>::value || !VectorTraits<T>::canInitializeWithMemset, "Cannot initialize with memset if there is a vtable");
-        static_assert(Allocator::isGarbageCollected || !AllowsOnlyPlacementNew<T>::value || !NeedsTracing<T>::value, "Cannot put DISALLOW_NEW_EXCEPT_PLACEMENT_NEW objects that have trace methods into an off-heap Vector");
+        static_assert(Allocator::isGarbageCollected || !AllowsOnlyPlacementNew<T>::value || !IsTraceable<T>::value, "Cannot put DISALLOW_NEW_EXCEPT_PLACEMENT_NEW objects that have trace methods into an off-heap Vector");
         static_assert(Allocator::isGarbageCollected || !IsPointerToGarbageCollectedType<T>::value, "Cannot put raw pointers to garbage-collected classes into an off-heap Vector.  Use HeapVector<Member<T>> instead.");
 
         ANNOTATE_NEW_BUFFER(begin(), capacity(), size);
@@ -1523,7 +1523,7 @@ void Vector<T, inlineCapacity, Allocator>::trace(VisitorDispatcher visitor)
     }
     const T* bufferBegin = buffer();
     const T* bufferEnd = buffer() + size();
-    if (NeedsTracingTrait<VectorTraits<T>>::value) {
+    if (IsTraceableInCollectionTrait<VectorTraits<T>>::value) {
         for (const T* bufferEntry = bufferBegin; bufferEntry != bufferEnd; bufferEntry++)
             Allocator::template trace<VisitorDispatcher, T, VectorTraits<T>>(visitor, *const_cast<T*>(bufferEntry));
         checkUnusedSlots(buffer() + size(), buffer() + capacity());