[Prerender] Ignores resources with unsupported schemes for Offline reqs

[Prerender] Ignores resources with unsupported schemes for Offline reqs

For offlining a page with the prerender, this changes the policy when
encountering a resource with an unsupported scheme - instread of failing
the prerender (as is done with other prerender requests), it will only
cancel the unsupported resource and attempt to continue with prerendering.

This has been tested end-end on 5 articles linked from www.foxsports.com
that have a "blob:" subresource and with this change, we are able to
download and offline version of them.

BUG=686192
Review-Url: https://codereview.chromium.org/2661703002
Cr-Commit-Position: refs/heads/master@{#449337}
(cherry picked from commit f1ba435af9338792a78fc422eb9cd1a51a14aa13)

Review-Url: https://codereview.chromium.org/2687173002 .
Cr-Commit-Position: refs/branch-heads/2987@{#417}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/0aeb5cf9de7fd0003d7a4323ab46e5e10d500d30

[Pete Williamson, 2017-02-09 21:27:17]

Description was changed from

==========
[Prerender] Ignores resources with unsupported schemes for Offline reqs

For offlining a page with the prerender, this changes the policy when
encountering a resource with an unsupported scheme - instread of failing
the prerender (as is done with other prerender requests), it will only
cancel the unsupported resource and attempt to continue with prerendering.

This has been tested end-end on 5 articles linked from www.foxsports.com
that have a "blob:" subresource and with this change, we are able to
download and offline version of them.

BUG=686192

Review-Url: https://codereview.chromium.org/2661703002
Cr-Commit-Position: refs/heads/master@{#449337}
(cherry picked from commit f1ba435af9338792a78fc422eb9cd1a51a14aa13)
==========

to

==========
[Prerender] Ignores resources with unsupported schemes for Offline reqs

For offlining a page with the prerender, this changes the policy when
encountering a resource with an unsupported scheme - instread of failing
the prerender (as is done with other prerender requests), it will only
cancel the unsupported resource and attempt to continue with prerendering.

This has been tested end-end on 5 articles linked from www.foxsports.com
that have a "blob:" subresource and with this change, we are able to
download and offline version of them.

BUG=686192

Review-Url: https://codereview.chromium.org/2661703002
Cr-Commit-Position: refs/heads/master@{#449337}
(cherry picked from commit f1ba435af9338792a78fc422eb9cd1a51a14aa13)

Review-Url: https://codereview.chromium.org/2687173002 .
Cr-Commit-Position: refs/branch-heads/2987@{#417}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/0aeb5cf9de7fd0003d7a4323ab46...
==========

[Pete Williamson, 2017-02-09 21:27:18]

Committed patchset #1 (id:1) manually as
0aeb5cf9de7fd0003d7a4323ab46e5e10d500d30.