[api] Allow label annotations for PersistentValueMapBase

Allows adding a label to strong retainers in PersistentValueMapBase and
its subclasses. These labels show up in DevTools and enable identifying
strong retainers of objects.

R: ulan@chromium.org
Change-Id: Id5e19507c40e44688c82a4caec89449b563a0e8b
Reviewed-on: https://chromium-review.googlesource.com/c/1372069Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58177}

include/v8-util.h

@@ -287,7 +287,10 @@ class PersistentValueMapBase {
   }
 
  protected:
-  explicit PersistentValueMapBase(Isolate* isolate) : isolate_(isolate) {}
+  explicit PersistentValueMapBase(Isolate* isolate)
+      : isolate_(isolate), label_(nullptr) {}
+  PersistentValueMapBase(Isolate* isolate, const char* label)
+      : isolate_(isolate), label_(label) {}
 
   ~PersistentValueMapBase() { Clear(); }
 
@@ -329,6 +332,10 @@ class PersistentValueMapBase {
     p.Reset();
   }
 
+  void AnnotateStrongRetainer(Global<V>* persistent) {
+    persistent->AnnotateStrongRetainer(label_);
+  }
+
  private:
   PersistentValueMapBase(PersistentValueMapBase&);
   void operator=(PersistentValueMapBase&);
@@ -345,6 +352,7 @@ class PersistentValueMapBase {
 
   Isolate* isolate_;
   typename Traits::Impl impl_;
+  const char* label_;
 };
 
 
@@ -353,6 +361,8 @@ class PersistentValueMap : public PersistentValueMapBase<K, V, Traits> {
  public:
   explicit PersistentValueMap(Isolate* isolate)
       : PersistentValueMapBase<K, V, Traits>(isolate) {}
+  PersistentValueMap(Isolate* isolate, const char* label)
+      : PersistentValueMapBase<K, V, Traits>(isolate, label) {}
 
   typedef
       typename PersistentValueMapBase<K, V, Traits>::PersistentValueReference
@@ -380,7 +390,9 @@ class PersistentValueMap : public PersistentValueMapBase<K, V, Traits> {
    * by the Traits class.
    */
   Global<V> SetUnique(const K& key, Global<V>* persistent) {
-    if (Traits::kCallbackType != kNotWeak) {
+    if (Traits::kCallbackType == kNotWeak) {
+      this->AnnotateStrongRetainer(persistent);
+    } else {
       WeakCallbackType callback_type =
           Traits::kCallbackType == kWeakWithInternalFields
               ? WeakCallbackType::kInternalFields
@@ -425,6 +437,8 @@ class GlobalValueMap : public PersistentValueMapBase<K, V, Traits> {
  public:
   explicit GlobalValueMap(Isolate* isolate)
       : PersistentValueMapBase<K, V, Traits>(isolate) {}
+  GlobalValueMap(Isolate* isolate, const char* label)
+      : PersistentValueMapBase<K, V, Traits>(isolate, label) {}
 
   typedef
       typename PersistentValueMapBase<K, V, Traits>::PersistentValueReference
@@ -452,7 +466,9 @@ class GlobalValueMap : public PersistentValueMapBase<K, V, Traits> {
    * by the Traits class.
    */
   Global<V> SetUnique(const K& key, Global<V>* persistent) {
-    if (Traits::kCallbackType != kNotWeak) {
+    if (Traits::kCallbackType == kNotWeak) {
+      this->AnnotateStrongRetainer(persistent);
+    } else {
       WeakCallbackType callback_type =
           Traits::kCallbackType == kWeakWithInternalFields
               ? WeakCallbackType::kInternalFields