Move the writing of the MHTML footer to the browser process.

third_party/WebKit/public/web/WebFrameSerializer.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 77 matching lines @@
   // savable resources underneath.
   //
   // Same |boundary| needs to used for all generateMHTMLHeader and
   // generateMHTMLParts and generateMHTMLFooter calls that belong to the same
   // MHTML document (see also rfc1341, section 7.2.1, "boundary" description).
   BLINK_EXPORT static WebThreadSafeData generateMHTMLParts(
       const WebString& boundary,
       WebLocalFrame*,
       MHTMLPartsGenerationDelegate*);
 
-  // Generates and returns an MHTML footer.
-  //
-  // Same |boundary| needs to used for all generateMHTMLHeader and
-  // generateMHTMLParts and generateMHTMLFooter calls that belong to the same
-  // MHTML document (see also rfc1341, section 7.2.1, "boundary" description).
-  BLINK_EXPORT static WebThreadSafeData generateMHTMLFooter(
-      const WebString& boundary);

[dcheng, 2017/03/09 01:56:51]

For symmetry, it would be nice to remove generateMHTMLHeader() from the public
API as well. Would it be possible to do that in a followup?

[carlosk, 2017/03/09 22:03:36]

I am still considering it (you can see it mentioned in the referred issue). Even
though I appreciate the symmetry aspect the header requires more data and more
tooling on that I still have to figure out I can practically obtain/use from
inside content/.

[dcheng, 2017/03/09 22:08:46]

My concern is that the interaction between Blink and content for page
serialization is already very complicated, and not having a consistent interface
will be a long-term maintenance burden. The dependencies on title and mime type
should both be satisfiable from content: WebDocument has a title getter, and the
WebDataSource of the frame points to the response, which has an associated MIME
type.

[carlosk, 2017/03/09 23:07:29]

Acknowledged.

[dcheng, 2017/03/09 23:09:17]

To clarify, does that mean you'll be investigating now or in a followup? If it's
a followup, do you mind filing a bug and adding a TODO so we don't lose track of
this?

[carlosk, 2017/03/09 23:13:45]

Not now. I will keep the linked issue (https://crbug.com/672292) open anyway
until I look into that.

-
   // IMPORTANT:
   // The API below is an older implementation of frame serialization that
   // will be removed soon.
 
   class LinkRewritingDelegate {
    public:
     // Method allowing the delegate control which URLs are written into the
     // generated html document.
     //
     // When URL of the given frame needs to be rewritten, this method should
@@ skipping 35 matching lines @@
   // Generate the MOTW declaration.
   BLINK_EXPORT static WebString generateMarkOfTheWebDeclaration(const WebURL&);
   // Generate the default base tag declaration.
   BLINK_EXPORT static WebString generateBaseTagDeclaration(
       const WebString& baseTarget);
 };
 
 }  // namespace blink
 
 #endif