Enable storing TrackableObject in other C++ class

atom/browser/api/trackable_object.cc

@@ -4,8 +4,28 @@
 
 #include "atom/browser/api/trackable_object.h"
 
+#include "base/supports_user_data.h"
+
 namespace mate {
 
+namespace {
+
+const char* kTrackedObjectKey = "TrackedObjectKey";
+
+class IDUserData : public base::SupportsUserData::Data {
+ public:
+  explicit IDUserData(int32_t id) : id_(id) {}
+
+  operator int32_t() const { return id_; }
+
+ private:
+  int32_t id_;
+
+  DISALLOW_COPY_AND_ASSIGN(IDUserData);
+};
+
+}  // namespace
+
 atom::IDWeakMap TrackableObject::weak_map_;
 
 // static
@@ -20,6 +40,15 @@ TrackableObject* TrackableObject::FromWeakMapID(v8::Isolate* isolate,
   return self;
 }
 
+// static
+TrackableObject* TrackableObject::FromWrappedClass(
+    v8::Isolate* isolate, base::SupportsUserData* wrapped) {
+  auto id = static_cast<IDUserData*>(wrapped->GetUserData(kTrackedObjectKey));
+  if (!id)
+    return nullptr;
+  return FromWeakMapID(isolate, *id);
+}
+
 // static
 void TrackableObject::ReleaseAllWeakReferences() {
   weak_map_.Clear();
@@ -36,4 +65,8 @@ void TrackableObject::AfterInit(v8::Isolate* isolate) {
   weak_map_id_ = weak_map_.Add(isolate, GetWrapper(isolate));
 }
 
+void TrackableObject::Attach(base::SupportsUserData* wrapped) {
+  wrapped->SetUserData(kTrackedObjectKey, new IDUserData(weak_map_id_));
+}
+
 }  // namespace mate

atom/browser/api/trackable_object.h

@@ -8,15 +8,23 @@
 #include "atom/browser/api/event_emitter.h"
 #include "atom/common/id_weak_map.h"
 
+namespace base {
+class SupportsUserData;
+}
+
 namespace mate {
 
 // All instances of TrackableObject will be kept in a weak map and can be got
 // from its ID.
 class TrackableObject : public mate::EventEmitter {
  public:
-  // Find out the TrackableObject from its ID in weak map:
+  // Find out the TrackableObject from its ID in weak map.
   static TrackableObject* FromWeakMapID(v8::Isolate* isolate, int32_t id);
 
+  // Find out the TrackableObject from the class it wraps.
+  static TrackableObject* FromWrappedClass(
+      v8::Isolate* isolate, base::SupportsUserData* wrapped);
+
   // Releases all weak references in weak map, called when app is terminating.
   static void ReleaseAllWeakReferences();
 
@@ -30,6 +38,9 @@ class TrackableObject : public mate::EventEmitter {
   TrackableObject();
   ~TrackableObject() override;
 
+  // Wrap TrackableObject into a class that SupportsUserData.
+  void Attach(base::SupportsUserData* wrapped);
+
  private:
   static atom::IDWeakMap weak_map_;