v8binding: Remove unnecessary v8::Persistent from IDL callbacks

This is a quick fix to remove v8::Persistent from IDL callbacks.
V8PersistentCallback{Function,Interface}Base should be removed
in a follow-up patch.

Change-Id: Ic6526252749e6d70c8c02092ae0b07716702e176
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1645713Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666283}

third_party/blink/renderer/platform/bindings/callback_function_base.cc

@@ -86,15 +86,6 @@ void CallbackFunctionBase::EvaluateAsPartOfCallback(
   std::move(closure).Run();
 }
 
-V8PersistentCallbackFunctionBase::V8PersistentCallbackFunctionBase(
-    CallbackFunctionBase* callback_function)
-    : callback_function_(callback_function) {
-  v8::Isolate* isolate = callback_function_->GetIsolate();
-  v8::HandleScope scope(isolate);
-  auto local = callback_function_->callback_function_.NewLocal(isolate);
-  v8_function_.Reset(isolate, local);
-}
-
 void V8PersistentCallbackFunctionBase::Trace(blink::Visitor* visitor) {
   visitor->Trace(callback_function_);
 }

third_party/blink/renderer/platform/bindings/callback_function_base.h

@@ -112,6 +112,8 @@ class PLATFORM_EXPORT CallbackFunctionBase
   friend class V8PersistentCallbackFunctionBase;
 };
 
+// CAUTION: THIS CLASS IS OBSOLETE AFTER THE UNIFIED HEAP AND WILL BE REMOVED.
+//
 // V8PersistentCallbackFunctionBase retains the underlying v8::Function of a
 // CallbackFunctionBase without wrapper-tracing. This class is necessary and
 // useful where wrapper-tracing is not suitable. Remember that, as a nature of
@@ -122,12 +124,14 @@ class PLATFORM_EXPORT CallbackFunctionBase
 class PLATFORM_EXPORT V8PersistentCallbackFunctionBase
     : public GarbageCollectedFinalized<V8PersistentCallbackFunctionBase> {
  public:
-  virtual ~V8PersistentCallbackFunctionBase() { v8_function_.Reset(); }
+  virtual ~V8PersistentCallbackFunctionBase() = default;
 
   virtual void Trace(blink::Visitor*);
 
  protected:
-  explicit V8PersistentCallbackFunctionBase(CallbackFunctionBase*);
+  explicit V8PersistentCallbackFunctionBase(
+      CallbackFunctionBase* callback_function)
+      : callback_function_(callback_function) {}
 
   template <typename V8CallbackFunction>
   V8CallbackFunction* As() {
@@ -139,9 +143,6 @@ class PLATFORM_EXPORT V8PersistentCallbackFunctionBase
 
  private:
   Member<CallbackFunctionBase> callback_function_;
-  // Use v8::Object instead of v8::Function in order to handle
-  // [TreatNonObjectAsNull].
-  v8::Persistent<v8::Object> v8_function_;
 };
 
 // V8PersistentCallbackFunction<V8CallbackFunction> is a counter-part of

third_party/blink/renderer/platform/bindings/callback_interface_base.cc

@@ -72,15 +72,6 @@ ScriptState* CallbackInterfaceBase::CallbackRelevantScriptStateOrThrowException(
   return nullptr;
 }
 
-V8PersistentCallbackInterfaceBase::V8PersistentCallbackInterfaceBase(
-    CallbackInterfaceBase* callback_interface)
-    : callback_interface_(callback_interface) {
-  v8::Isolate* isolate = callback_interface_->GetIsolate();
-  v8::HandleScope scope(isolate);
-  auto local = callback_interface_->callback_object_.NewLocal(isolate);
-  v8_object_.Reset(isolate, local);
-}
-
 void V8PersistentCallbackInterfaceBase::Trace(blink::Visitor* visitor) {
   visitor->Trace(callback_interface_);
 }

third_party/blink/renderer/platform/bindings/callback_interface_base.h

@@ -109,6 +109,8 @@ class PLATFORM_EXPORT CallbackInterfaceBase
   friend class V8PersistentCallbackInterfaceBase;
 };
 
+// CAUTION: THIS CLASS IS OBSOLETE AFTER THE UNIFIED HEAP AND WILL BE REMOVED.
+//
 // V8PersistentCallbackInterfaceBase retains the underlying v8::Object of a
 // CallbackInterfaceBase without wrapper-tracing. This class is necessary and
 // useful where wrapper-tracing is not suitable. Remember that, as a nature of
@@ -119,14 +121,16 @@ class PLATFORM_EXPORT CallbackInterfaceBase
 class PLATFORM_EXPORT V8PersistentCallbackInterfaceBase
     : public GarbageCollectedFinalized<V8PersistentCallbackInterfaceBase> {
  public:
-  virtual ~V8PersistentCallbackInterfaceBase() { v8_object_.Reset(); }
+  virtual ~V8PersistentCallbackInterfaceBase() = default;
 
   virtual void Trace(blink::Visitor*);
 
   v8::Isolate* GetIsolate() { return callback_interface_->GetIsolate(); }
 
  protected:
-  explicit V8PersistentCallbackInterfaceBase(CallbackInterfaceBase*);
+  explicit V8PersistentCallbackInterfaceBase(
+      CallbackInterfaceBase* callback_interface)
+      : callback_interface_(callback_interface) {}
 
   template <typename V8CallbackInterface>
   V8CallbackInterface* As() {
@@ -138,7 +142,6 @@ class PLATFORM_EXPORT V8PersistentCallbackInterfaceBase
 
  private:
   Member<CallbackInterfaceBase> callback_interface_;
-  v8::Persistent<v8::Object> v8_object_;
 };
 
 // V8PersistentCallbackInterface<V8CallbackInterface> is a counter-part of