Fix crasher if onBeforeSendHeaders contains no new headers

Fix crasher if onBeforeSendHeaders contains no new headers


BUG=104046
TEST=run webrequest extension with chrome.webRequest.onBeforeSendHeaders.addListener(function(details) {return {cancel: true};}, {urls: ["<all_urls>"]}, ["blocking"]);


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=113901

[battre, 2011-12-09 16:25:08]

Please review. Thanks.

[Matt Perry, 2011-12-09 19:50:01]

lgtm

[commit-bot: I haz the power, 2011-12-09 20:19:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/battre@chromium.org/8894003/1

[commit-bot: I haz the power, 2011-12-09 22:28:26]

Try job failure for 8894003-1 (retry) on linux_rel for step "ui_tests".
It's a second try, previously, step "ui_tests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[commit-bot: I haz the power, 2011-12-09 23:01:44]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/battre@chromium.org/8894003/1

[commit-bot: I haz the power, 2011-12-10 00:49:43]

Change committed as 113901