Oilpan: enable appcache + move DocumentLoader to the heap.

Source/web/WebDataSourceImpl.cpp

Index: Source/web/WebDataSourceImpl.cpp
diff --git a/Source/web/WebDataSourceImpl.cpp b/Source/web/WebDataSourceImpl.cpp
index 8bdb7a1fcd6916bc86ab02f5fe1f584a5b87ba65..4b7bbd809aaca47d0c081cdfee0d344e455127a2 100644
--- a/Source/web/WebDataSourceImpl.cpp
+++ b/Source/web/WebDataSourceImpl.cpp
@@ -44,9 +44,9 @@ static OwnPtr<WebPluginLoadObserver>& nextPluginLoadObserver()
     return nextPluginLoadObserver;
 }
 
-PassRefPtr<WebDataSourceImpl> WebDataSourceImpl::create(LocalFrame* frame, const ResourceRequest& request, const SubstituteData& data)
+PassRefPtrWillBeRawPtr<WebDataSourceImpl> WebDataSourceImpl::create(LocalFrame* frame, const ResourceRequest& request, const SubstituteData& data)
 {
-    return adoptRef(new WebDataSourceImpl(frame, request, data));
+    return adoptRefWillBeNoop(new WebDataSourceImpl(frame, request, data));
 }
 
 const WebURLRequest& WebDataSourceImpl::originalRequest() const
@@ -160,6 +160,22 @@ WebDataSourceImpl::WebDataSourceImpl(LocalFrame* frame, const ResourceRequest& r
 
 WebDataSourceImpl::~WebDataSourceImpl()
 {
+    // Verify that detachFromFrame() has been called.
+    ASSERT(!m_extraData);
+}
+
+void WebDataSourceImpl::detachFromFrame()
+{
+    RefPtrWillBeRawPtr<DocumentLoader> protect(this);
+
+    DocumentLoader::detachFromFrame();
+    m_extraData.clear();
+    m_pluginLoadObserver.clear();
+}
+
+DEFINE_TRACE(WebDataSourceImpl)
+{
+    DocumentLoader::trace(visitor);
 }
 
 } // namespace blink