Oilpan: have FrameFetchContext keep a DocumentLoader member.

Source/core/loader/FrameFetchContext.cpp

Index: Source/core/loader/FrameFetchContext.cpp
diff --git a/Source/core/loader/FrameFetchContext.cpp b/Source/core/loader/FrameFetchContext.cpp
index 0c9d982bd7832cb3e0b233e4ea53db919a2ecda6..208b1c540e5eb3ec74590b6b9117d6e78e68bbb0 100644
--- a/Source/core/loader/FrameFetchContext.cpp
+++ b/Source/core/loader/FrameFetchContext.cpp
@@ -197,7 +197,7 @@ ResourceRequestCachePolicy FrameFetchContext::resourceRequestCachePolicy(const R
 // cannot see imported documents.
 inline DocumentLoader* FrameFetchContext::ensureLoaderForNotifications()
 {
-    return m_documentLoader ? m_documentLoader : frame()->loader().documentLoader();
+    return m_documentLoader ? m_documentLoader.get() : frame()->loader().documentLoader();
 }
 
 void FrameFetchContext::dispatchDidChangeResourcePriority(unsigned long identifier, ResourceLoadPriority loadPriority, int intraPriorityValue)
@@ -664,6 +664,7 @@ bool FrameFetchContext::isLowPriorityIframe() const
 DEFINE_TRACE(FrameFetchContext)
 {
     visitor->trace(m_document);
+    visitor->trace(m_documentLoader);
     FetchContext::trace(visitor);
 }