Chrome: FAIL - 66.0.3334.0 (Official Build) canary (64-bit)
Firefox: OK
     IE: OK

1. drag'n'drop any local HTML or PDF file into the omnibox (addressbar), observe
2. drag'n'drop an URL from some tab's omnibox into another tab's omnibox, observe

Expected: the URL is opened automatically
Observed: the URL is pasted but not navigated

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Bisect info: 531166 (good) - 531169 (bad)
https://chromium.googlesource.com/chromium/src/+log/17f235af..577cfecf?pretty=fuller
Suspecting r531167 = 620133d59810d54853d1095e9fc98903d1b1790a = https://crrev.com/c/873110 by sangwoo108@gmail.com
"Don't auto-navigate on drop into omnibox"
Landed in 66.0.3330.0

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The rationale in  issue 791259  was to prevent automatic searching of plain text using the default search engine, however r531167 has broken the historical feature supported in all browsers for 10+ years - navigating to an URL drag'n'dropped into omnibox e.g. from another tab. It was very convenient to be able to drag URLs from other tabs/windows or from other browsers.