Fail when saving page as MHTML provides information about the cause.

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index a17b198447e048b9986418c4b6d3446bfc040ba4..6428542d10bd8cf8de040553c24d39d1a6e6b7bd 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -2163,11 +2163,11 @@ void RenderFrameHostImpl::OnDidChangeLoadProgress(double load_progress) {
 
 void RenderFrameHostImpl::OnSerializeAsMHTMLResponse(
     int job_id,
-    bool success,
+    MhtmlSaveStatus save_status,
     const std::set<std::string>& digests_of_uris_of_serialized_resources,
     base::TimeDelta renderer_main_thread_time) {
   MHTMLGenerationManager::GetInstance()->OnSerializeAsMHTMLResponse(
-      this, job_id, success, digests_of_uris_of_serialized_resources,
+      this, job_id, save_status, digests_of_uris_of_serialized_resources,
       renderer_main_thread_time);
 }