Store non-standard HTTP headers in history

We currently have the ability to set extra HTTP header fields in WebURLRequest.  However, the extra HTTP header fields are not stored in WebHistoryItem and are therefore lost after navigation. Non-standard HTTP headers, usually prefixed with 'X-', are used by a number of server-based applications and represent a safe subset of extra HTTP headers that can be stored in the history. This patch works in combination with the patch for the below WebKit issue to support storage and recall of non-standard HTTP headers.

https://bugs.webkit.org/show_bug.cgi?id=26994

[Marshall Greenblatt, 2009-09-23 17:36:24]

Please review this patch.  This is my first attempt at a two-sided patch so any
feedback on the correct process is welcome :-).

[Marshall Greenblatt, 2009-09-23 17:42:04]

The WebKit side of this patch is available here:
http://codereview.chromium.org/220010

[darin (slow to review), 2009-09-23 19:51:22]

http://codereview.chromium.org/225012/diff/1/4
File webkit/api/public/WebHistoryItem.h (right):

http://codereview.chromium.org/225012/diff/1/4#newcode111
Line 111: WEBKIT_API void visitExtraHTTPHeaders(WebHTTPHeaderVisitor*) const;
It seems like it would be nice to use the same names as the methods on
WebURLRequest.

setExtraHTTPHeader -> setHTTPHeaderField
visitExtraHTTPHeaders -> visitHTTPHeaderFields

http://codereview.chromium.org/225012/diff/1/3
File webkit/api/src/WebHistoryItem.cpp (right):

http://codereview.chromium.org/225012/diff/1/3#newcode257
Line 257: visitor->visitHeader(it->first, it->second);
nit: webkit style is to not have {}'s around single line statements.

http://codereview.chromium.org/225012/diff/1/2
File webkit/glue/glue_serialize.cc (right):

http://codereview.chromium.org/225012/diff/1/2#newcode54
Line 54: // 5: Adds support for empty FormData
you need to be careful here.  since you are changing the binary format of the
history serialization, it can break session restore in chrome.  you need to make
sure that you support the old binary format, and to facilitate that you need to
bump the version number and add supporting code down below.

[Marshall Greenblatt, 2009-09-23 20:45:59]

Please review the updated patch set. There's a good discussion happening on the
WebKit side ( https://bugs.webkit.org/show_bug.cgi?id=26994 )-- if anyone wants
to chime in, feedback there would be appreciated too :-).