[Offline pages] Update background loader to override the WebContentsObserver methods expected

chrome/browser/android/offline_pages/background_loader_offliner.cc

Index: chrome/browser/android/offline_pages/background_loader_offliner.cc
diff --git a/chrome/browser/android/offline_pages/background_loader_offliner.cc b/chrome/browser/android/offline_pages/background_loader_offliner.cc
index faf7d50e8bec4b86ba7e3bb121f8c1f8ccbc65e8..083add47622a6d94c91500260066a1448e3c931d 100644
--- a/chrome/browser/android/offline_pages/background_loader_offliner.cc
+++ b/chrome/browser/android/offline_pages/background_loader_offliner.cc
@@ -205,7 +205,7 @@ void BackgroundLoaderOffliner::DocumentLoadedInFrame(
     content::RenderFrameHost* render_host) {
   // Inform snapshot controller if in main frame.
   if (!render_host->GetParent())
-    snapshot_controller_->DocumentAvailableInMainFrame();
+    snapshot_controller_->DocumentLoadedInMainFrame();
 }
 
 void BackgroundLoaderOffliner::DidStopLoading() {
@@ -214,7 +214,7 @@ void BackgroundLoaderOffliner::DidStopLoading() {
     return;
   }
 
-  snapshot_controller_->DocumentOnLoadCompletedInMainFrame();
+  snapshot_controller_->DidStopLoading();
 }
 
 void BackgroundLoaderOffliner::RenderProcessGone(