[Offline pages] Check errors and invalidate pointers only for mainframe for navigation

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 9246ff6c086d9097e971c403a5472cc7447c84c2..dad0627bb278241d61ebf97df7adccbedcc29400 100644
--- a/chrome/browser/android/offline_pages/background_loader_offliner.cc
+++ b/chrome/browser/android/offline_pages/background_loader_offliner.cc
@@ -228,6 +228,8 @@ void BackgroundLoaderOffliner::WebContentsDestroyed() {
 
 void BackgroundLoaderOffliner::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
+  if (!navigation_handle->IsInMainFrame())
+    return;
   // If there was an error of any kind (certificate, client, DNS, etc),
   // Mark as error page. Resetting here causes RecordNavigationMetrics to crash.
   if (navigation_handle->IsErrorPage()) {
@@ -264,7 +266,7 @@ void BackgroundLoaderOffliner::DidFinishNavigation(
     }
   }
 
-  // If the page is not the same, invalidate any pending save tasks.
+  // If the document is not the same invalidate any pending save tasks.
   //
   // Downloads or 204/205 response codes do not commit (no new navigation)
   // Same-Page (committed) navigations are: