Fix Docs links from Files app on ChromeOS not working with PlzNavigate.

Fix Docs links from Files app on ChromeOS not working with PlzNavigate.

The cause was that there was a redirect from externalfile scheme to https. The PlzNavigate code chose the right ending process based on the final URL. However when the renderer made a request for the stream URL, it does attach the original URL (pre-redirect) along. ResourceDispatcherHostImpl::ShouldServiceRequest was incorrectly aborting the URL because that process rightly does not have access to the externalfile scheme.

The fix is to skip the ChildProcessSecurityPolicy::CanRequestURL check in ShouldServiceRequest for the PlzNavigate stream request. The browser already picked the right process, and the stream URL is unguessable. The change also skips most of ContinuePendingBeginRequest() and CreateResourceHandler() for PlzNavigate stream requests to minimize the risk that they contain code that could be exploited.

BUG=717644
Review-Url: https://codereview.chromium.org/2908593002
Cr-Original-Commit-Position: refs/heads/master@{#475097}
Review-Url: https://codereview.chromium.org/2910063003 .
Cr-Commit-Position: refs/branch-heads/3112@{#31}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed: https://chromium.googlesource.com/chromium/src/+/12c73ea1a9ada42efdc3e2b245e718214d6f3125

[jam, 2017-05-30 16:21:23]

Description was changed from

==========
Fix Docs links from Files app on ChromeOS not working with PlzNavigate.

The cause was that there was a redirect from externalfile scheme to https. The
PlzNavigate code chose the right ending process based on the final URL. However
when the renderer made a request for the stream URL, it does attach the original
URL (pre-redirect) along. ResourceDispatcherHostImpl::ShouldServiceRequest was
incorrectly aborting the URL because that process rightly does not have access
to the externalfile scheme.

The fix is to skip the ChildProcessSecurityPolicy::CanRequestURL check in
ShouldServiceRequest for the PlzNavigate stream request. The browser already
picked the right process, and the stream URL is unguessable. The change also
skips most of ContinuePendingBeginRequest() and CreateResourceHandler() for
PlzNavigate stream requests to minimize the risk that they contain code that
could be exploited.

BUG=717644

Review-Url: https://codereview.chromium.org/2908593002
Cr-Commit-Position: refs/heads/master@{#475097}
(cherry picked from commit ecb25eb8968a45120ee434af2d3da30baebc6b63)
==========

to

==========
Fix Docs links from Files app on ChromeOS not working with PlzNavigate.

The cause was that there was a redirect from externalfile scheme to https. The
PlzNavigate code chose the right ending process based on the final URL. However
when the renderer made a request for the stream URL, it does attach the original
URL (pre-redirect) along. ResourceDispatcherHostImpl::ShouldServiceRequest was
incorrectly aborting the URL because that process rightly does not have access
to the externalfile scheme.

The fix is to skip the ChildProcessSecurityPolicy::CanRequestURL check in
ShouldServiceRequest for the PlzNavigate stream request. The browser already
picked the right process, and the stream URL is unguessable. The change also
skips most of ContinuePendingBeginRequest() and CreateResourceHandler() for
PlzNavigate stream requests to minimize the risk that they contain code that
could be exploited.

BUG=717644

Review-Url: https://codereview.chromium.org/2908593002
Cr-Original-Commit-Position: refs/heads/master@{#475097}
Review-Url: https://codereview.chromium.org/2910063003 .
Cr-Commit-Position: refs/branch-heads/3112@{#31}
Cr-Branched-From:
b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed:
https://chromium.googlesource.com/chromium/src/+/12c73ea1a9ada42efdc3e2b245e7...
==========

[jam, 2017-05-30 16:21:24]

Committed patchset #1 (id:1) manually as
12c73ea1a9ada42efdc3e2b245e718214d6f3125.