Remove ResourceFetcher's access to a real FetchContext at frame detach time

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 750f73b6455e2990f556896849a4fa594e0ae5ad..e6dbf1221c14dccf4e0dac19dfa61dbe4d9a3762 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -480,11 +480,13 @@ Document::Document(const DocumentInit& initializer, DocumentClassFlags documentC
         provideContextFeaturesToDocumentFrom(*this, *m_frame->page());
 
         m_fetcher = m_frame->loader().documentLoader()->fetcher();
-    }
-
-    if (!m_fetcher)
+        FrameFetchContext::provideDocumentToContext(m_fetcher->context(), this);
+    } else if (m_importsController) {
         m_fetcher = FrameFetchContext::createContextAndFetcher(nullptr);
-    static_cast<FrameFetchContext&>(m_fetcher->context()).setDocument(this);
+        FrameFetchContext::provideDocumentToContext(m_fetcher->context(), this);
+    } else {
+        m_fetcher = ResourceFetcher::create(nullptr);
+    }
 
     // We depend on the url getting immediately set in subframes, but we
     // also depend on the url NOT getting immediately set in opened windows.
@@ -574,13 +576,6 @@ Document::~Document()
     if (m_elemSheet)
         m_elemSheet->clearOwnerNode();
 
-    // It's possible for multiple Documents to end up referencing the same ResourceFetcher (e.g., SVGImages
-    // load the initial empty document and the SVGDocument with the same DocumentLoader).
-    FrameFetchContext& context = static_cast<FrameFetchContext&>(m_fetcher->context());
-    if (context.document() == this)
-        context.setDocument(nullptr);
-    m_fetcher.clear();
-
     // We must call clearRareData() here since a Document class inherits TreeScope
     // as well as Node. See a comment on TreeScope.h for the reason.
     if (hasRareData())
@@ -836,6 +831,8 @@ void Document::setImportsController(HTMLImportsController* controller)
 {
     ASSERT(!m_importsController || !controller);
     m_importsController = controller;
+    if (!m_importsController)
+        m_fetcher->clearContext();
 }
 
 HTMLImportLoader* Document::importLoader() const
@@ -2140,6 +2137,14 @@ void Document::detach(const AttachContext& context)
 
     frameHost()->eventHandlerRegistry().documentDetached(*this);
 
+    // If this Document is associated with a live DocumentLoader, the
+    // DocumentLoader will take care of clearing the FetchContext. Deferring
+    // to the DocumentLoader when possible also prevents prematurely clearing
+    // the context in the case where multiple Documents end up associated with
+    // a single DocumentLoader (e.g., navigating to a javascript: url).
+    if (!loader())
+        m_fetcher->clearContext();
+
     // This is required, as our LocalFrame might delete itself as soon as it detaches
     // us. However, this violates Node::detach() semantics, as it's never
     // possible to re-attach. Eventually Document::detach() should be renamed,