Make context initialization order deterministic in WebFrame::swap().

third_party/WebKit/Source/bindings/core/v8/WindowProxyManager.h

 // 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.
 
 #ifndef WindowProxyManager_h
 #define WindowProxyManager_h
 
 #include <utility>
 
 #include "bindings/core/v8/LocalWindowProxy.h"
@@ skipping 12 matching lines @@
 
 class WindowProxyManagerBase : public GarbageCollected<WindowProxyManagerBase> {
  public:
   DECLARE_TRACE();
 
   v8::Isolate* isolate() const { return m_isolate; }
 
   void clearForClose();
   void CORE_EXPORT clearForNavigation();
 
-  void CORE_EXPORT
-  releaseGlobals(HashMap<DOMWrapperWorld*, v8::Local<v8::Object>>&);
-  void CORE_EXPORT
-  setGlobals(const HashMap<DOMWrapperWorld*, v8::Local<v8::Object>>&);
+  using GlobalsVector =
+      Vector<std::pair<DOMWrapperWorld*, v8::Local<v8::Object>>>;

[haraken, 2017/03/09 22:04:46]

Would you add a comment and explain why this needs to be a vector?

[dcheng, 2017/03/09 22:10:20]

I thought about asking for a comment, but it felt like a very fragile comment:
if something in the embedder changes and it starts getting an isolated world
context *while* initializing the main context, we'll have similar issues. So
this is kind of a bandaid fix while the extensions code is fixed (but is still
useful to have, because deterministic initialization seems like a good thing).

[Alexander Semashko, 2017/03/09 22:26:10]

Added a comment. Is it ok?

+  void CORE_EXPORT releaseGlobals(GlobalsVector&);
+  void CORE_EXPORT setGlobals(const GlobalsVector&);
 
  protected:
   using IsolatedWorldMap = HeapHashMap<int, Member<WindowProxy>>;
 
   explicit WindowProxyManagerBase(Frame&);
 
   Frame* frame() const { return m_frame; }
   WindowProxy* mainWorldProxy() const { return m_windowProxy.get(); }
   WindowProxy* windowProxy(DOMWrapperWorld&);
 
@@ skipping 52 matching lines @@
   }
 
  private:
   explicit RemoteWindowProxyManager(RemoteFrame& frame)
       : WindowProxyManagerImplHelper<RemoteFrame, RemoteWindowProxy>(frame) {}
 };
 
 }  // namespace blink
 
 #endif  // WindowProxyManager_h