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 5fee5bf452a8c6375bd263059b599b6a28256a9a..ebf976fd4de5922724c44b55915956d14022e6d7 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -2136,11 +2136,11 @@ 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);
 }