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

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 2118 matching lines @@
   if (is_active())
     frame_tree_node_->DidStopLoading();
 }
 
 void RenderFrameHostImpl::OnDidChangeLoadProgress(double load_progress) {
   frame_tree_node_->DidChangeLoadProgress(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);
 }
 
 void RenderFrameHostImpl::OnSelectionChanged(const base::string16& text,
                                              uint32_t offset,
                                              const gfx::Range& range) {
   has_selection_ = !text.empty();
   GetRenderWidgetHost()->SelectionChanged(text, offset, range);
 }
 
@@ skipping 1150 matching lines @@
   // There is no pending NavigationEntry in these cases, so pass 0 as the
   // pending_nav_entry_id. If the previous handle was a prematurely aborted
   // navigation loaded via LoadDataWithBaseURL, propagate the entry id.
   return NavigationHandleImpl::Create(
       params.url, frame_tree_node_, is_renderer_initiated,
       params.was_within_same_page, params.is_srcdoc, base::TimeTicks::Now(),
       entry_id_for_data_nav, false);  // started_from_context_menu
 }
 
 }  // namespace content