Reland "Correctly set ScriptState in the image loader microtask"

Source/core/loader/ImageLoader.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/loader/ImageLoader.h"
 
 #include "bindings/core/v8/ScriptController.h"
+#include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8PerIsolateData.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/dom/IncrementLoadEventDelayCount.h"
 #include "core/dom/Microtask.h"
 #include "core/events/Event.h"
 #include "core/events/EventSender.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/MemoryCache.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 42 matching lines @@
     {
         return adoptPtr(new Task(loader, updateBehavior));
     }
 
     Task(ImageLoader* loader, UpdateFromElementBehavior updateBehavior)
         : m_loader(loader)
         , m_shouldBypassMainWorldCSP(shouldBypassMainWorldCSP(loader))
         , m_updateBehavior(updateBehavior)
         , m_weakFactory(this)
     {
+        v8::Isolate* isolate = V8PerIsolateData::mainThreadIsolate();
+        v8::HandleScope scope(isolate);
+        v8::Local<v8::Context> context = isolate->GetCurrentContext();
+        // If we're invoked from C++ without a V8 context on the stack, we should
+        // run the microtask in the context of the element's document's main world.
+        if (context.IsEmpty())
+            m_scriptState = ScriptState::from(toV8Context(&loader->element()->document(), DOMWrapperWorld::mainWorld()));
+        else
+            m_scriptState = ScriptState::from(context);
     }
 
-    virtual void run() override
+    ~Task() override
+    {
+    }
+
+    void run() override
     {
         if (m_loader) {
 #if ENABLE(OILPAN)
             // Oilpan: this WebThread::Task microtask may run after the
             // loader has been GCed, but not yet lazily swept & finalized
             // (when this task's loader reference will be cleared.)
             //
             // Handle this transient condition by explicitly checking here
             // before going ahead with the update operation. Unsafe to do it
             // if so, as the objects that the loader refers to may have been
             // finalized by this time.
             if (Heap::willObjectBeLazilySwept(m_loader))
                 return;
 #endif
-            m_loader->doUpdateFromElement(m_shouldBypassMainWorldCSP, m_updateBehavior);
+            if (m_scriptState->contextIsValid()) {
+                ScriptState::Scope scope(m_scriptState.get());
+                m_loader->doUpdateFromElement(m_shouldBypassMainWorldCSP, m_updateBehavior);
+            } else {
+                m_loader->doUpdateFromElement(m_shouldBypassMainWorldCSP, m_updateBehavior);

[haraken, 2015/05/28 11:48:58]

It's not clear that this never reaches shouldBypassMainWorldCSP(). Shall we add
some comments or ASSERTs to verify that this code doesn't reach anything that
requires a context?

+            }
         }
     }
 
     void clearLoader()
     {
         m_loader = 0;
+        m_scriptState.clear();
     }
 
     WeakPtr<Task> createWeakPtr()
     {
         return m_weakFactory.createWeakPtr();
     }
 
 private:
     ImageLoader* m_loader;
     BypassMainWorldBehavior m_shouldBypassMainWorldCSP;
     UpdateFromElementBehavior m_updateBehavior;
+    RefPtr<ScriptState> m_scriptState;
     WeakPtrFactory<Task> m_weakFactory;
 };
 
 ImageLoader::ImageLoader(Element* element)
     : m_element(element)
     , m_image(0)
     , m_derefElementTimer(this, &ImageLoader::timerFired)
     , m_hasPendingLoadEvent(false)
     , m_hasPendingErrorEvent(false)
     , m_imageComplete(true)
@@ skipping 489 matching lines @@
 #endif
 }
 
 #if ENABLE(OILPAN)
 ImageLoader::ImageLoaderClientRemover::~ImageLoaderClientRemover()
 {
     m_loader.willRemoveClient(m_client);
 }
 #endif
 }