PlzNavigate: Make BlockLegacySubresources work.

Chrome blocks 'ftp:' subresource request inside 'http'/'https' pages.

It was broken with PlzNavigate (--enable-browser-side-navigation) when
the subresource is an iframe. The page was blocked, but only after the
request had been sent to the server.
This CL makes chrome block requests before they are submitted.

Additionnally, it removes the
--enable-blink-feature=BlockLegacySubresources switch. It should be
removed for M60 and this patch will land for M62.

Test: NavigationHandleImplBrowserTest.BlockLegacySubresources
Bug: 757809,435547
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_browser_side_navigation_rel;master.tryserver.chromium.linux:linux_site_isolation
Change-Id: Ia85417af453b2e0532b0b7c0f381fa8a2f8e6e8a
Commit-Queue: Arthur Sonzogni <>
Reviewed-by: Camille Lamy <>
Reviewed-by: Mike West <>
Cr-Commit-Position: refs/heads/master@{#498476}
6 files changed