Create distiller files for Reading List.

ios/chrome/browser/dom_distiller/distiller_viewer.h

Index: ios/chrome/browser/dom_distiller/distiller_viewer.h
diff --git a/ios/chrome/browser/dom_distiller/distiller_viewer.h b/ios/chrome/browser/dom_distiller/distiller_viewer.h
index 639b7ea66770ba92dff110b5d4194d5df7a4880b..25a99efcdbd03dd2e4da999621d5d31d16631be7 100644
--- a/ios/chrome/browser/dom_distiller/distiller_viewer.h
+++ b/ios/chrome/browser/dom_distiller/distiller_viewer.h
@@ -51,10 +51,17 @@ class DistillerViewerInterface : public DomDistillerRequestViewBase {
 // A very simple and naive implementation of the DistillerViewer.
 class DistillerViewer : public DistillerViewerInterface {
  public:
+  // Creates a |DistillerView| that will be used to distill |url|.
+  // If |factory| is not null, it will be used to create the DistillerPage that
+  // will load the URL and distill the page. If |factory| is null, the default
+  // factory of |distillerService| will be used.
+  // |callback| is called when distillation is finished with the protobuf
+  // containing the distilled page.
   DistillerViewer(dom_distiller::DomDistillerService* distillerService,
                   PrefService* prefs,
                   const GURL& url,
-                  const DistillationFinishedCallback& callback);
+                  const DistillationFinishedCallback& callback,
+                  const DistillerPageFactory* factory);
   ~DistillerViewer() override;
 
   void OnArticleReady(