The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/07205c9be7b8fa35aa6079b6027f6261761b62c3

commit 07205c9be7b8fa35aa6079b6027f6261761b62c3
Author: ryansturm <ryansturm@chromium.org>
Date: Wed Feb 22 07:08:33 2017

Adding MHTML support into Page Load Metrics

Offline Previews metrics will not be reported currently because the
MIME-type sniffing only allows text/html or application/xhtml+xml.
MHTML, entires pages saved as one file are mime-type multipart/related
(https://en.wikipedia.org/wiki/MIME#Multipart_subtypes). Offline
previews are treated as HTTP/HTTPS MHTML pages from the perspective of
the chrome page load metrics harness, and treated as HTML documents in
blink. This should mean that offline pages are the only class of MHTML
pages that will be tracked in the harness.

BUG= 693776 

Review-Url: https://codereview.chromium.org/2699213002
Cr-Commit-Position: refs/heads/master@{#451906}

[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/browser/page_load_metrics/browser_page_track_decider.cc
[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc
[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.h
[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/browser/page_load_metrics/page_load_metrics_observer.h
[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/browser/page_load_metrics/page_load_tracker.cc
[modify] https://crrev.com/07205c9be7b8fa35aa6079b6027f6261761b62c3/chrome/renderer/page_load_metrics/renderer_page_track_decider.cc

Your change meets the bar and is auto-approved for M57. Please go ahead and merge the CL to branch 2987 manually. Please contact milestone owner if you have questions.
Owners: amineer@(clank), cmasso@(bling), ketakid@(cros), govind@(desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/df8c967bc255fe10a4d9a4c34b5094afc0868958

commit df8c967bc255fe10a4d9a4c34b5094afc0868958
Author: Ryan Sturm <ryansturm@chromium.org>
Date: Wed Feb 22 16:41:40 2017

Adding MHTML support into Page Load Metrics

Offline Previews metrics will not be reported currently because the
MIME-type sniffing only allows text/html or application/xhtml+xml.
MHTML, entires pages saved as one file are mime-type multipart/related
(https://en.wikipedia.org/wiki/MIME#Multipart_subtypes). Offline
previews are treated as HTTP/HTTPS MHTML pages from the perspective of
the chrome page load metrics harness, and treated as HTML documents in
blink. This should mean that offline pages are the only class of MHTML
pages that will be tracked in the harness.

BUG= 693776 

Review-Url: https://codereview.chromium.org/2699213002
Cr-Commit-Position: refs/heads/master@{#451906}
(cherry picked from commit 07205c9be7b8fa35aa6079b6027f6261761b62c3)

Review-Url: https://codereview.chromium.org/2708213005 .
Cr-Commit-Position: refs/branch-heads/2987@{#642}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}

[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/browser/page_load_metrics/browser_page_track_decider.cc
[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc
[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.h
[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/browser/page_load_metrics/page_load_metrics_observer.h
[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/browser/page_load_metrics/page_load_tracker.cc
[modify] https://crrev.com/df8c967bc255fe10a4d9a4c34b5094afc0868958/chrome/renderer/page_load_metrics/renderer_page_track_decider.cc