[profiler] Query retainer infos from embedder instead of using object grouping

src/profiler/heap-snapshot-generator.cc

Index: src/profiler/heap-snapshot-generator.cc
diff --git a/src/profiler/heap-snapshot-generator.cc b/src/profiler/heap-snapshot-generator.cc
index c84892b069d6a7c28b3224136bbf35a6759fee0e..f62129726643d267bdf6fb0c790949c711eeb6a7 100644
--- a/src/profiler/heap-snapshot-generator.cc
+++ b/src/profiler/heap-snapshot-generator.cc
@@ -4,6 +4,8 @@
 
 #include "src/profiler/heap-snapshot-generator.h"
 
+#include <utility>
+
 #include "src/code-stubs.h"
 #include "src/conversions.h"
 #include "src/debug/debug.h"
@@ -2287,55 +2289,52 @@ int NativeObjectsExplorer::EstimateObjectsCount() {
 
 void NativeObjectsExplorer::FillRetainedObjects() {
   if (embedder_queried_) return;
-  Isolate* isolate = isolate_;
-  const GCType major_gc_type = kGCTypeMarkSweepCompact;
-  // Record objects that are joined into ObjectGroups.
-  isolate->heap()->CallGCPrologueCallbacks(
-      major_gc_type, kGCCallbackFlagConstructRetainedObjectInfos);
-  List<ObjectGroup*>* groups = isolate->global_handles()->object_groups();
-  for (int i = 0; i < groups->length(); ++i) {
-    ObjectGroup* group = groups->at(i);
-    if (group->info == NULL) continue;
-    List<HeapObject*>* list = GetListMaybeDisposeInfo(group->info);
-    for (size_t j = 0; j < group->length; ++j) {
-      HeapObject* obj = HeapObject::cast(*group->objects[j]);
-      list->Add(obj);
-      in_groups_.Insert(obj);
+  v8::HandleScope scope(reinterpret_cast<v8::Isolate*>(isolate_));
+  v8::HeapProfiler::RetainerInfos infos =
+      snapshot_->profiler()->GetRetainerInfos(isolate_);
+  for (auto& pair : infos.groups) {
+    List<HeapObject*>* list = GetListMaybeDisposeInfo(pair.first);
+    for (auto& persistent : pair.second) {
+      if (persistent->IsEmpty()) continue;
+
+      Handle<Object> object = v8::Utils::OpenHandle(
+          *persistent->Get(reinterpret_cast<v8::Isolate*>(isolate_)));
+      DCHECK(!object.is_null());
+      HeapObject* heap_object = HeapObject::cast(*object);
+      list->Add(heap_object);
+      in_groups_.Insert(heap_object);
     }
-    group->info = NULL;  // Acquire info object ownership.
   }
-  isolate->global_handles()->RemoveObjectGroups();
-  isolate->heap()->CallGCEpilogueCallbacks(major_gc_type, kNoGCCallbackFlags);
+
   // Record objects that are not in ObjectGroups, but have class ID.
   GlobalHandlesExtractor extractor(this);
-  isolate->global_handles()->IterateAllRootsWithClassIds(&extractor);
+  isolate_->global_handles()->IterateAllRootsWithClassIds(&extractor);
+
+  edges_ = std::move(infos.edges);
   embedder_queried_ = true;
 }
 
+void NativeObjectsExplorer::FillEdges() {
+  v8::HandleScope scope(reinterpret_cast<v8::Isolate*>(isolate_));
+  // Fill in actual edges found.
+  for (auto& pair : edges_) {
+    if (pair.first->IsEmpty() || pair.second->IsEmpty()) continue;
 
-void NativeObjectsExplorer::FillImplicitReferences() {
-  Isolate* isolate = isolate_;
-  List<ImplicitRefGroup*>* groups =
-      isolate->global_handles()->implicit_ref_groups();
-  for (int i = 0; i < groups->length(); ++i) {
-    ImplicitRefGroup* group = groups->at(i);
-    HeapObject* parent = *group->parent;
+    Handle<Object> parent_object = v8::Utils::OpenHandle(
+        *pair.first->Get(reinterpret_cast<v8::Isolate*>(isolate_)));
+    HeapObject* parent = HeapObject::cast(*parent_object);
     int parent_entry =
         filler_->FindOrAddEntry(parent, native_entries_allocator_)->index();
     DCHECK(parent_entry != HeapEntry::kNoEntry);
-    Object*** children = group->children;
-    for (size_t j = 0; j < group->length; ++j) {
-      Object* child = *children[j];
-      HeapEntry* child_entry =
-          filler_->FindOrAddEntry(child, native_entries_allocator_);
-      filler_->SetNamedReference(
-          HeapGraphEdge::kInternal,
-          parent_entry,
-          "native",
-          child_entry);
-    }
+    Handle<Object> child_object = v8::Utils::OpenHandle(
+        *pair.second->Get(reinterpret_cast<v8::Isolate*>(isolate_)));
+    HeapObject* child = HeapObject::cast(*child_object);
+    HeapEntry* child_entry =
+        filler_->FindOrAddEntry(child, native_entries_allocator_);
+    filler_->SetNamedReference(HeapGraphEdge::kInternal, parent_entry, "native",
+                               child_entry);
   }
-  isolate->global_handles()->RemoveImplicitRefGroups();
+  edges_.clear();
 }
 
 List<HeapObject*>* NativeObjectsExplorer::GetListMaybeDisposeInfo(
@@ -2355,7 +2354,7 @@ bool NativeObjectsExplorer::IterateAndExtractReferences(
     SnapshotFiller* filler) {
   filler_ = filler;
   FillRetainedObjects();
-  FillImplicitReferences();
+  FillEdges();
   if (EstimateObjectsCount() > 0) {
     for (base::HashMap::Entry* p = objects_by_info_.Start(); p != NULL;
          p = objects_by_info_.Next(p)) {