Extract code to mark an object during incremental marking

Not only does this remove code duplication, I also plan to use this for
unifying reference group marking later

BUG=none
R=hpayer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1007793002

Cr-Commit-Position: refs/heads/master@{#27180}

src/heap/incremental-marking.cc

@@ -251,13 +251,7 @@ class IncrementalMarkingMarkingVisitor
 
   // Marks the object grey and pushes it on the marking stack.
   INLINE(static void MarkObject(Heap* heap, Object* obj)) {
-    HeapObject* heap_object = HeapObject::cast(obj);
-    MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
-    if (mark_bit.data_only()) {
-      MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
-    } else if (Marking::IsWhite(mark_bit)) {
-      heap->incremental_marking()->WhiteToGreyAndPush(heap_object, mark_bit);
-    }
+    IncrementalMarking::MarkObject(heap, obj);
   }
 
   // Marks the object black without pushing it on the marking stack.
@@ -280,7 +274,7 @@ class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
  public:
   explicit IncrementalMarkingRootMarkingVisitor(
       IncrementalMarking* incremental_marking)
-      : incremental_marking_(incremental_marking) {}
+      : heap_(incremental_marking->heap()) {}
 
   void VisitPointer(Object** p) { MarkObjectByPointer(p); }
 
@@ -293,18 +287,10 @@ class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
     Object* obj = *p;
     if (!obj->IsHeapObject()) return;
 
-    HeapObject* heap_object = HeapObject::cast(obj);
-    MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
-    if (mark_bit.data_only()) {
-      MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
-    } else {
-      if (Marking::IsWhite(mark_bit)) {
-        incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
-      }
-    }
+    IncrementalMarking::MarkObject(heap_, obj);
   }
 
-  IncrementalMarking* incremental_marking_;
+  Heap* heap_;
 };
 
 
@@ -639,6 +625,17 @@ void IncrementalMarking::VisitObject(Map* map, HeapObject* obj, int size) {
 }
 
 
+void IncrementalMarking::MarkObject(Heap* heap, Object* obj) {
+  HeapObject* heap_object = HeapObject::cast(obj);
+  MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
+  if (mark_bit.data_only()) {
+    MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
+  } else if (Marking::IsWhite(mark_bit)) {
+    heap->incremental_marking()->WhiteToGreyAndPush(heap_object, mark_bit);
+  }
+}
+
+
 intptr_t IncrementalMarking::ProcessMarkingDeque(intptr_t bytes_to_process) {
   intptr_t bytes_processed = 0;
   Map* filler_map = heap_->one_pointer_filler_map();

src/heap/incremental-marking.h

@@ -189,6 +189,10 @@ class IncrementalMarking {
 
   bool IsIdleMarkingDelayCounterLimitReached();
 
+  INLINE(static void MarkObject(Heap* heap, Object* object));
+
+  Heap* heap() const { return heap_; }
+
  private:
   int64_t SpaceLeftInOldSpace();