blink_gc_plugin: detect singletons with embedded ScriptWrappables.

tools/clang/blink_gc_plugin/RecordInfo.cpp

Index: tools/clang/blink_gc_plugin/RecordInfo.cpp
diff --git a/tools/clang/blink_gc_plugin/RecordInfo.cpp b/tools/clang/blink_gc_plugin/RecordInfo.cpp
index 419ed7ae764ce261f18e8986ac26d7aff52a98be..2bce77147605fdd0ad16dfc66399f998a508f6d1 100644
--- a/tools/clang/blink_gc_plugin/RecordInfo.cpp
+++ b/tools/clang/blink_gc_plugin/RecordInfo.cpp
@@ -107,6 +107,27 @@ CXXRecordDecl* RecordInfo::GetDependentTemplatedDecl(const Type& type) {
   return dyn_cast_or_null<CXXRecordDecl>(tmpl_decl->getTemplatedDecl());
 }
 
+const Type* RecordInfo::GetPersistentArgumentType(bool& has_persistent_name) {
+  has_persistent_name =
+      Config::IsPersistent(name()) || Config::IsCrossThreadPersistent(name());
+  if (!has_persistent_name)
+    return nullptr;
+
+  // "Persistent" could refer to v8::Persistent, check the name space.
+  if (!IsInBlinkNamespace())
+    return nullptr;
+
+  TemplateArgs args;
+  if (!GetTemplateArgs(1, &args))
+    return nullptr;
+  return args[0];
+}
+
+bool RecordInfo::IsInBlinkNamespace() {
+  NamespaceDecl* ns = dyn_cast<NamespaceDecl>(record()->getDeclContext());
+  return ns && ns->getName() == "blink";
+}
+
 void RecordInfo::walkBases() {
   // This traversal is akin to CXXRecordDecl::forallBases()'s,
   // but without stepping over dependent bases -- these might also
@@ -514,20 +535,23 @@ bool RecordInfo::NeedsFinalization() {
       return does_need_finalization_;
 
     CXXDestructorDecl* dtor = record_->getDestructor();
-    if (dtor && dtor->isUserProvided())
+    if (dtor && dtor->isUserProvided()) {
       return does_need_finalization_;
+    }
     for (Fields::iterator it = GetFields().begin();
          it != GetFields().end();
          ++it) {
-      if (it->second.edge()->NeedsFinalization())
+      if (it->second.edge()->NeedsFinalization()) {
         return does_need_finalization_;
+      }
     }
 
     for (Bases::iterator it = GetBases().begin();
          it != GetBases().end();
          ++it) {
-      if (it->second.info()->NeedsFinalization())
+      if (it->second.info()->NeedsFinalization()) {
         return does_need_finalization_;
+      }
     }
     // Destructor was non-trivial due to bases with destructors that
     // can be safely ignored. Hence, no need for finalization.
@@ -655,23 +679,19 @@ Edge* RecordInfo::CreateEdge(const Type* type) {
     return 0;
   }
 
-  bool is_persistent = Config::IsPersistent(info->name());
-  if (is_persistent || Config::IsCrossThreadPersistent(info->name())) {
-    // Persistent might refer to v8::Persistent, so check the name space.
-    // TODO: Consider using a more canonical identification than names.
-    NamespaceDecl* ns =
-        dyn_cast<NamespaceDecl>(info->record()->getDeclContext());
-    if (!ns || ns->getName() != "blink")
-      return 0;
-    if (!info->GetTemplateArgs(1, &args))
-      return 0;
-    if (Edge* ptr = CreateEdge(args[0])) {
-      if (is_persistent)
+  bool has_persistent_name = false;
+  if (const Type* arg_type =
+          info->GetPersistentArgumentType(has_persistent_name)) {
+    if (Edge* ptr = CreateEdge(arg_type)) {
+      if (Config::IsPersistent(info->name()))
         return new Persistent(ptr);
       else
         return new CrossThreadPersistent(ptr);
     }
-    return 0;
+    return nullptr;
+  } else if (has_persistent_name) {
+    // Other Persistent type names are not relevant, like v8::Persistent<>.
+    return nullptr;
   }
 
   if (Config::IsGCCollection(info->name()) ||