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

content/browser/frame_host/render_frame_host_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 11 matching lines @@
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/bad_message.h"
 #include "content/browser/loader/global_routing_id.h"
 #include "content/browser/site_instance_impl.h"
 #include "content/browser/webui/web_ui_impl.h"
 #include "content/common/accessibility_mode_enums.h"
 #include "content/common/ax_content_node_data.h"
 #include "content/common/content_export.h"
+#include "content/common/download/mhtml_save_status.h"
 #include "content/common/frame.mojom.h"
 #include "content/common/frame_message_enums.h"
 #include "content/common/frame_replication_state.h"
 #include "content/common/image_downloader/image_downloader.mojom.h"
 #include "content/common/navigation_params.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/common/javascript_message_type.h"
 #include "media/mojo/interfaces/interface_factory.mojom.h"
 #include "net/http/http_response_headers.h"
 #include "services/service_manager/public/cpp/interface_factory.h"
@@ skipping 647 matching lines @@
                                               int hit_obj_id);
   void OnAccessibilitySnapshotResponse(
       int callback_id,
       const AXContentTreeUpdate& snapshot);
   void OnToggleFullscreen(bool enter_fullscreen);
   void OnDidStartLoading(bool to_different_document);
   void OnDidStopLoading();
   void OnDidChangeLoadProgress(double load_progress);
   void 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);
   void OnSelectionChanged(const base::string16& text,
                           uint32_t offset,
                           const gfx::Range& range);
 
 #if defined(USE_EXTERNAL_POPUP_MENU)
   void OnShowPopup(const FrameHostMsg_ShowPopup_Params& params);
   void OnHidePopup();
 #endif
@@ skipping 360 matching lines @@
       remote_associated_interfaces_;
   // NOTE: This must be the last member.
   base::WeakPtrFactory<RenderFrameHostImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_IMPL_H_