binding: Changes the association among global-proxy/global/window-instance.

third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
index ad0f11b1d9bf46d062554580886b5ca12c7cc158..cbd5aa209d3e5cf01ea410bf386202cc6f359e92 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8GCController.cpp
@@ -458,7 +458,9 @@ void V8GCController::collectAllGarbageForTesting(v8::Isolate* isolate) {
 
 class DOMWrapperTracer : public v8::PersistentHandleVisitor {
  public:
-  explicit DOMWrapperTracer(Visitor* visitor) : m_visitor(visitor) {}
+  explicit DOMWrapperTracer(Visitor* visitor) : m_visitor(visitor) {
+    DCHECK(m_visitor);
+  }
 
   void VisitPersistentHandle(v8::Persistent<v8::Value>* value,
                              uint16_t classId) override {
@@ -469,8 +471,10 @@ class DOMWrapperTracer : public v8::PersistentHandleVisitor {
     const v8::Persistent<v8::Object>& wrapper =
         v8::Persistent<v8::Object>::Cast(*value);
 
-    if (m_visitor)
-      toWrapperTypeInfo(wrapper)->trace(m_visitor, toScriptWrappable(wrapper));
+    // |scriptWrappable| can be null if |wrapper| is a global proxy object,
+    // which points to nothing while a navigation.

[haraken, 2017/02/09 12:46:40]

Move this comment to toScriptWrappable.

[Yuki, 2017/02/10 07:47:21]

Done.

+    if (ScriptWrappable* scriptWrappable = toScriptWrappable(wrapper))
+      toWrapperTypeInfo(wrapper)->trace(m_visitor, scriptWrappable);
   }
 
  private: