Offline Pages: Replace Observer::OfflinePageModelChanged with OfflinePageAdded.

components/offline_pages/offline_page_model.h

Index: components/offline_pages/offline_page_model.h
diff --git a/components/offline_pages/offline_page_model.h b/components/offline_pages/offline_page_model.h
index 8c8142cf36e168e26ab4b069d25aeb64c8f580a2..3acce9f5e8463ae66daa25cd0c85a38829eeb7db 100644
--- a/components/offline_pages/offline_page_model.h
+++ b/components/offline_pages/offline_page_model.h
@@ -78,9 +78,9 @@ class OfflinePageModel : public base::SupportsUserData {
     // Invoked when the model has finished loading.
     virtual void OfflinePageModelLoaded(OfflinePageModel* model) = 0;
 
-    // Invoked when the model is being updated, due to adding, removing or
-    // updating an offline page.
-    virtual void OfflinePageModelChanged(OfflinePageModel* model) = 0;
+    // Invoked when the model is being updated due to adding an offline page.
+    virtual void OfflinePageAdded(OfflinePageModel* model,
+                                  const OfflinePageItem& added_page) = 0;
 
     // Invoked when an offline copy related to |offline_id| was deleted.
     virtual void OfflinePageDeleted(int64_t offline_id,