In e10s mode with parent-side intercept enabled we currently do a special internal redirect to the InterceptedHttpChannel. This redirect is "hidden" from the child process to avoid confusing the legacy child-side intercept code. An unfortunate consequence of this is that redirect handlers, like fetch API's, cannot do things like copy headers over to the new channel. We should work around this by copying the headers over automatically for this one special redirect case. Eventually this can be removed when the child-side intercept code is removed and the redirect is unhidden.

Comment on attachment 8985631 [details] [diff] [review] Automatically copy headers to the InterceptedHttpChannel when performing the special hidden internal redirect. r=valentin This patch copies non-standard headers to the InterceptedHttpChannel when do the special interception redirect in parent-side intercept mode. Please see the comment in the patch for a longer explanation.

Pushed by bkelly@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/d5ee1692bd3c Automatically copy headers to the InterceptedHttpChannel when performing the special hidden internal redirect. r=valentin