Oilpan: avoid creating a cyclic reference to InjectedScriptHost.

Source/bindings/core/v8/inspector/V8InjectedScriptHost.cpp

 // Copyright 2015 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 "config.h"
 #include "bindings/core/v8/inspector/V8InjectedScriptHost.h"
 
 #include "bindings/core/v8/BindingSecurity.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptValue.h"
@@ skipping 615 matching lines @@
 
 class WeakCallbackData final {
 public:
     WeakCallbackData(v8::Isolate* isolate, PassRefPtrWillBeRawPtr<InjectedScriptHost> host, v8::Local<v8::Object> wrapper)
         : m_host(host)
         , m_persistent(isolate, wrapper)
     {
         m_persistent.SetWeak(this, &WeakCallbackData::weakCallback, v8::WeakCallbackType::kParameter);
     }
 
-    RefPtrWillBePersistent<InjectedScriptHost> m_host;
+    // If kept as a strong Persistent<>, this back reference causes an Oilpan leak by
+    // way of v8. Sidestep by using a raw pointer; InjectedScriptHost is slated to
+    // become a non-Oilpan object.
+    GC_PLUGIN_IGNORE("466631")
+    RefPtrWillBeRawPtr<InjectedScriptHost> m_host;
 
 private:
     static void weakCallback(const v8::WeakCallbackInfo<WeakCallbackData>& info)
     {
         delete info.GetParameter();
     }
 
     v8::Global<v8::Object> m_persistent;
 };
 
@@ skipping 46 matching lines @@
     void* data = value.As<v8::External>()->Value();
     return reinterpret_cast<WeakCallbackData*>(data)->m_host.get();
 }
 
 v8::Local<v8::String> V8InjectedScriptHost::hiddenPropertyName(v8::Isolate* isolate)
 {
     return v8::String::NewFromUtf8(isolate, "v8inspector::InjectedScriptHost", v8::NewStringType::kInternalized).ToLocalChecked();
 }
 
 } // namespace blink