Create retainment infos from handles, even for tracing

third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
index ba550a28e76deadff04231bc8ef97f5af452c36b..4a18f5f36f2f619450cafe6d96cecb15378d6a1d 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
@@ -151,11 +151,16 @@ class MinorGCUnmodifiedWrapperVisitor : public v8::PersistentHandleVisitor {
 class MajorGCWrapperVisitor : public v8::PersistentHandleVisitor {
  public:
   explicit MajorGCWrapperVisitor(v8::Isolate* isolate,
-                                 bool constructRetainedObjectInfos)
+                                 bool constructRetainedObjectInfos,
+                                 bool constructImplicitReferenceGroups)
       : m_isolate(isolate),
         m_domObjectsWithPendingActivity(0),
         m_liveRootGroupIdSet(false),
-        m_constructRetainedObjectInfos(constructRetainedObjectInfos) {}
+        m_constructRetainedObjectInfos(constructRetainedObjectInfos),
+        m_constructImplicitReferenceGroups(constructImplicitReferenceGroups) {
+    DCHECK(m_constructRetainedObjectInfos ||
+           m_constructImplicitReferenceGroups);
+  }
 
   void VisitPersistentHandle(v8::Persistent<v8::Value>* value,
                              uint16_t classId) override {
@@ -202,8 +207,10 @@ class MajorGCWrapperVisitor : public v8::PersistentHandleVisitor {
       if (m_constructRetainedObjectInfos)
         m_groupsWhichNeedRetainerInfo.append(root);
     } else if (classId == WrapperTypeInfo::ObjectClassId) {
-      type->visitDOMWrapper(m_isolate, toScriptWrappable(wrapper),
-                            v8::Persistent<v8::Object>::Cast(*value));
+      if (m_constructImplicitReferenceGroups) {

[haraken, 2016/10/04 11:24:48]

I'd directly use !RuntimeEnabledFeatures::traceWrappablesEnabled() and avoid
introducing an indirection variable like m_constructImplicitReferenceGroups.

[Michael Lippautz, 2016/10/04 11:31:02]

Done.

+        type->visitDOMWrapper(m_isolate, toScriptWrappable(wrapper),
+                              v8::Persistent<v8::Object>::Cast(*value));
+      }
     } else {
       NOTREACHED();
     }
@@ -253,6 +260,7 @@ class MajorGCWrapperVisitor : public v8::PersistentHandleVisitor {
   int m_domObjectsWithPendingActivity;
   bool m_liveRootGroupIdSet;
   bool m_constructRetainedObjectInfos;
+  bool m_constructImplicitReferenceGroups;
 };
 
 static unsigned long long usedHeapSize(v8::Isolate* isolate) {
@@ -269,17 +277,21 @@ void visitWeakHandlesForMinorGC(v8::Isolate* isolate) {
 }
 
 void objectGroupingForMajorGC(v8::Isolate* isolate,
-                              bool constructRetainedObjectInfos) {
-  MajorGCWrapperVisitor visitor(isolate, constructRetainedObjectInfos);
+                              bool constructRetainedObjectInfos,
+                              bool constructImplicitReferenceGroups) {

[haraken, 2016/10/04 11:24:48]

constructImplicitReferenceGroups is unused.

[Michael Lippautz, 2016/10/04 11:31:02]

Done.

+  MajorGCWrapperVisitor visitor(
+      isolate, constructRetainedObjectInfos,
+      !RuntimeEnabledFeatures::traceWrappablesEnabled());
   isolate->VisitHandlesWithClassIds(&visitor);
   visitor.notifyFinished();
 }
 
 void gcPrologueForMajorGC(v8::Isolate* isolate,
                           bool constructRetainedObjectInfos) {
-  // TODO(hlopko): Collect retained object infos for heap profiler
-  if (!RuntimeEnabledFeatures::traceWrappablesEnabled()) {
-    objectGroupingForMajorGC(isolate, constructRetainedObjectInfos);
+  const bool objectGrouping = !RuntimeEnabledFeatures::traceWrappablesEnabled();
+  if (objectGrouping || constructRetainedObjectInfos) {
+    objectGroupingForMajorGC(isolate, constructRetainedObjectInfos,
+                             objectGrouping);
   }
 }