[oilpan] ListHashSetNode: Avoid marking in Trace method

Instead just forward to the Trace method of this visitor which will call
ListHashSetNode::Trace after marking the node.

Bug: chromium:802273
Change-Id: Ic13090edead2e26c94ce0f0157e3d3f6d1effcb3
Reviewed-on: https://chromium-review.googlesource.com/939823
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539786}

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

@@ -695,14 +695,7 @@ struct TraceInCollectionTrait<
       if (!HashTableHelper<Node*, typename Table::ExtractorType,
                            typename Table::KeyTraitsType>::
               IsEmptyOrDeletedBucket(array[i])) {
-        TraceListHashSetValue(visitor, array[i]->value_);
-        // Just mark the node without tracing because we already traced
-        // the contents, and there is no need to trace the next and
-        // prev fields since iterating over the hash table backing will
-        // find the whole chain.
-        // TODO(mlippautz): Remove cast.
-        reinterpret_cast<blink::MarkingVisitor*>(visitor)->MarkNoTracing(
-            array[i]);
+        visitor->Trace(array[i]);
       }
     }
     return false;
@@ -874,12 +867,7 @@ struct TraceInCollectionTrait<
     static_assert(IsTraceableInCollectionTrait<Traits>::value ||
                       Traits::kWeakHandlingFlag == WTF::kWeakHandling,
                   "T should not be traced");
-    TraceListHashSetValue(visitor, node->value_);
-    // Just mark the node without tracing because we already traced the
-    // contents, and there is no need to trace the next and prev fields
-    // since iterating over the hash table backing will find the whole
-    // chain.
-    visitor->MarkNoTracing(node);
+    visitor->Trace(node);
     return false;
   }
 };

third_party/WebKit/Source/platform/wtf/ListHashSet.h

@@ -447,10 +447,6 @@ class ListHashSetNode : public ListHashSetNodeBase<ValueArg> {
     allocator->Deallocate(this);
   }
 
-  // This is not called in normal tracing, but it is called if we find a
-  // pointer to a node on the stack using conservative scanning. Since the
-  // original ListHashSet may no longer exist we make sure to mark the
-  // neighbours in the chain too.
   template <typename VisitorDispatcher>
   void Trace(VisitorDispatcher visitor) {
     // The conservative stack scan can find nodes that have been removed