Reland of PlzNavigate: send SourceLocation when mixed content is found (patchset #1 id:1 of https://codereview.chromium.org/2765643002/ )

Reason for revert:
Turns out this patch was not the reason for those failures. Re-landing it back.

Original issue's description:
> Revert of PlzNavigate: send SourceLocation when mixed content is found (patchset #8 id:140001 of https://codereview.chromium.org/2745363004/ )
>
> Reason for revert:
> This enabled LayoutTests which started to fail:
>
> https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Mac10.11%20%28dbg%29/builds/7963
> https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Mac10.11%20%28dbg%29/builds/7964
> https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Mac10.11%20%28dbg%29/builds/7965
>
> There are text failures and a DCHECK:
> 14:48:10.177 5284 worker/2 virtual/mojo-loading/http/tests/serviceworker/chromium/request-body-blob-crash.html crashed, (stderr lines):
> 14:48:10.177 5284   [9083:38659:0320/144810.106602:2775098818460:FATAL:url_request.cc(1205)] Check failed: blocked_by_.empty().
>
> Original issue's description:
> > PlzNavigate: send SourceLocation when mixed content is found
> >
> > This CL adds SourceLocation information to the IPC
> > FrameMsg_MixedContentFound so that Mixed Contents console error messages
> > display the appropriate line number. It also fixes an issue due to the
> > rebase of https://codereview.chromium.org/2720763002/, where the
> > SourceLocation information was not properly copied in the pending
> > navigation info in RenderFrameImpl.
> >
> > BUG=695072
> > CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation
> >
> > Review-Url: https://codereview.chromium.org/2745363004
> > Cr-Commit-Position: refs/heads/master@{#458068}
> > Committed: https://chromium.googlesource.com/chromium/src/+/8a58df54d52b781b9628e7adee559157a8602150
>
> [email protected],[email protected],[email protected],[email protected]
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=695072
>
> Review-Url: https://codereview.chromium.org/2765643002
> Cr-Commit-Position: refs/heads/master@{#458245}
> Committed: https://chromium.googlesource.com/chromium/src/+/54c5f4ac7707c8e5d5341eae008fa5f303f7656c

[email protected],[email protected],[email protected],[email protected]
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=695072

Review-Url: https://codereview.chromium.org/2760263002
Cr-Commit-Position: refs/heads/master@{#458311}
12 files changed