Add incremental updates for multipage distillation.

components/dom_distiller/content/dom_distiller_viewer_source.cc

Index: components/dom_distiller/content/dom_distiller_viewer_source.cc
diff --git a/components/dom_distiller/content/dom_distiller_viewer_source.cc b/components/dom_distiller/content/dom_distiller_viewer_source.cc
index 56aa0e83b8ca76714b4746ab5d724293f6e296aa..4538eb5c6a9c4e3477c1bb595e5e2b979eecd8f4 100644
--- a/components/dom_distiller/content/dom_distiller_viewer_source.cc
+++ b/components/dom_distiller/content/dom_distiller_viewer_source.cc
@@ -59,6 +59,9 @@ class DomDistillerViewerSource::RequestViewerHandle
   virtual void OnArticleReady(const DistilledArticleProto* article_proto)
       OVERRIDE;
 
+  virtual void OnArticleUpdated(ArticleDistillationUpdate article_update)
+      OVERRIDE;
+
   void TakeViewerHandle(scoped_ptr<ViewerHandle> viewer_handle);
 
  private:
@@ -102,6 +105,11 @@ void DomDistillerViewerSource::RequestViewerHandle::OnArticleReady(
   base::MessageLoop::current()->DeleteSoon(FROM_HERE, this);
 }
 
+void DomDistillerViewerSource::RequestViewerHandle::OnArticleUpdated(
+    ArticleDistillationUpdate article_update) {
+  // TODO(nyquist): Add support for displaying pages incrementally.
+}
+
 void DomDistillerViewerSource::RequestViewerHandle::TakeViewerHandle(
     scoped_ptr<ViewerHandle> viewer_handle) {
   viewer_handle_ = viewer_handle.Pass();
@@ -179,7 +187,7 @@ bool DomDistillerViewerSource::ShouldServiceRequest(
 // TODO(nyquist): Start tracking requests using this method.
 void DomDistillerViewerSource::WillServiceRequest(
     const net::URLRequest* request,
-    std::string* path) const {};
+    std::string* path) const {}
 
 std::string DomDistillerViewerSource::GetContentSecurityPolicyObjectSrc()
     const {