[webkit-dev] Removing deprecatedFrameEncoding

Adam Barth abarth at webkit.org
Sun Jan 15 12:52:21 PST 2012

We've previously discussed this topic in Bug 67882 and Bug 75905.

We should remove deprecatedFrameEncoding.  Removing the code has the
following benefits:

1) Standards compliance.  There was a discussion in the HTTP working
group about whether the requesting context should be a factor in
determining the character set used to decode the Content-Disposition
header.  The working group decided that we shouldn't use that
information for several reasons:

  a) Varying the interpretation of an HTTP response based on the
context of the request is contrary to the stateless nature of HTTP.
The fact that HTTP request/response pairs can be understood
irrespective of context is core to the design of HTTP.

  b) Most user agents, including most browsers, do not have this
behavior.  That means the compatibility risk for dropping the behavior
in other user agents (e.g., Safari) is relatively low, especially for
a feature likes this one that is not widely used on the mobile web.

2) Stability.  This code crashes.  For example, in the most recent
release of Chrome Canary on Windows, deprecatedFrameEncoding accounts
for 3.5% of all renderer crashes.  While we could invest effort in
fixing these crashes, we'd be better off removing this code and
spending that effort improving stability elsewhere.

If removing deprecatedFrameEncoding isn't possible at this time, we
should revert http://trac.webkit.org/changeset/104723 because it
causes crashes.  Rather than get into a revert war, however, I believe
the project would be better served by talking out this issue.


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