Oilpan: enable appcache + move DocumentLoader to the heap.

Source/web/WebDataSourceImpl.h

Index: Source/web/WebDataSourceImpl.h
diff --git a/Source/web/WebDataSourceImpl.h b/Source/web/WebDataSourceImpl.h
index 601ca6ab2a182bcb8501a3c22898b8da61f18eab..717fdd7e929c0d53c32819df79ee46c6c17031a6 100644
--- a/Source/web/WebDataSourceImpl.h
+++ b/Source/web/WebDataSourceImpl.h
@@ -34,6 +34,7 @@
 #include "core/loader/DocumentLoader.h"
 #include "platform/exported/WrappedResourceRequest.h"
 #include "platform/exported/WrappedResourceResponse.h"
+#include "platform/heap/Handle.h"
 #include "platform/weborigin/KURL.h"
 #include "public/web/WebDataSource.h"
 #include "web/WebPluginLoadObserver.h"
@@ -47,7 +48,7 @@ class WebPluginLoadObserver;
 
 class WebDataSourceImpl final : public DocumentLoader, public WebDataSource {
 public:
-    static PassRefPtr<WebDataSourceImpl> create(LocalFrame*, const ResourceRequest&, const SubstituteData&);
+    static PassRefPtrWillBeRawPtr<WebDataSourceImpl> create(LocalFrame*, const ResourceRequest&, const SubstituteData&);
 
     static WebDataSourceImpl* fromDocumentLoader(DocumentLoader* loader)
     {
@@ -74,9 +75,12 @@ public:
     PassOwnPtr<WebPluginLoadObserver> releasePluginLoadObserver() { return m_pluginLoadObserver.release(); }
     static void setNextPluginLoadObserver(PassOwnPtr<WebPluginLoadObserver>);
 
+    DECLARE_VIRTUAL_TRACE();
+
 private:
     WebDataSourceImpl(LocalFrame*, const ResourceRequest&, const SubstituteData&);
     virtual ~WebDataSourceImpl();
+    virtual void detachFromFrame() override;
 
     // Mutable because the const getters will magically sync these to the
     // latest version from WebKit.