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

content/renderer/render_frame_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_RENDERER_RENDER_FRAME_IMPL_H_
 #define CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <deque>
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/id_map.h"
 #include "base/macros.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/process/process_handle.h"
 #include "build/build_config.h"
 #include "content/common/accessibility_mode_enums.h"
 #include "content/common/associated_interface_registry_impl.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/host_zoom.mojom.h"
 #include "content/common/renderer.mojom.h"
 #include "content/public/common/console_message_level.h"
 #include "content/public/common/javascript_message_type.h"
 #include "content/public/common/referrer.h"
 #include "content/public/common/stop_find_action.h"
 #include "content/public/renderer/render_frame.h"
 #include "content/renderer/frame_blame_context.h"
@@ skipping 841 matching lines @@
 #if defined(OS_MACOSX)
   void OnCopyToFindPboard();
 #endif
 
   // Callback scheduled from OnSerializeAsMHTML for when writing serialized
   // MHTML to file has been completed in the file thread.
   void OnWriteMHTMLToDiskComplete(
       int job_id,
       std::set<std::string> serialized_resources_uri_digests,
       base::TimeDelta main_thread_use_time,
-      bool success);
+      MhtmlSaveStatus save_status);
 
   // Requests that the browser process navigates to |url|. If
   // |is_history_navigation_in_new_child| is true, the browser process should
   // look for a matching FrameNavigationEntry in the last committed entry to use
   // instead of |url|.
   void OpenURL(
       const GURL& url,
       bool uses_post,
       const scoped_refptr<ResourceRequestBodyImpl>& resource_request_body,
       const std::string& extra_headers,
@@ skipping 438 matching lines @@
   bool browser_side_navigation_pending_ = false;
 
   base::WeakPtrFactory<RenderFrameImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_FRAME_IMPL_H_