gin: Bug fix: Fix CreateHandle to return an emtpy handle in some extreme cases

gin/wrappable.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gin/wrappable.h"
 
 #include "base/logging.h"
 #include "gin/object_template_builder.h"
 #include "gin/per_isolate_data.h"
 
@@ skipping 26 matching lines @@
 
   PerIsolateData* data = PerIsolateData::From(isolate);
   v8::Local<v8::ObjectTemplate> templ = data->GetObjectTemplate(info);
   if (templ.IsEmpty()) {
     templ = GetObjectTemplateBuilder(isolate).Build();
     CHECK(!templ.IsEmpty());
     data->SetObjectTemplate(info, templ);
   }
   CHECK_EQ(kNumberOfInternalFields, templ->InternalFieldCount());
   v8::Handle<v8::Object> wrapper = templ->NewInstance();
+  // |wrapper| may be empty in some extreme cases, e.g., when
+  // Object.prototype.constructor is overwritten.
+  if (wrapper.IsEmpty()) {
+    // The current wrappable object will be no longer managed by V8. Delete this
+    // now.
+    delete this;
+    return wrapper;
+  }
   wrapper->SetAlignedPointerInInternalField(kWrapperInfoIndex, info);
   wrapper->SetAlignedPointerInInternalField(kEncodedValueIndex, this);
   wrapper_.Reset(isolate, wrapper);
   wrapper_.SetWeak(this, WeakCallback);
   return wrapper;
 }
 
 namespace internal {
 
 void* FromV8Impl(v8::Isolate* isolate, v8::Handle<v8::Value> val,
@@ skipping 13 matching lines @@
   // instance of the C++ class associated with wrapper_info.
   if (info != wrapper_info)
     return NULL;
 
   return obj->GetAlignedPointerFromInternalField(kEncodedValueIndex);
 }
 
 }  // namespace internal
 
 }  // namespace gin