WIP CLs that fixes these: https://chromium-review.googlesource.com/c/catapult/+/968942
and patchset 5 -> 6 of this CL: https://chromium-review.googlesource.com/c/chromium/src/+/948623/5..6

Working on landing these.

I believe the change in behavior started at this CL: https://chromium-review.googlesource.com/c/catapult/+/937701

Current in progress CLs:
https://chromium-review.googlesource.com/c/catapult/+/968942 and
https://chromium-review.googlesource.com/c/chromium/src/+/975986

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7d0fcf3dfdf86ce127391d431cbe028f09607da6

commit 7d0fcf3dfdf86ce127391d431cbe028f09607da6
Author: Deepanjan Roy <dproy@chromium.org>
Date: Fri Mar 23 13:49:59 2018

Dump more information in navigation_start event

Today for metric calculations, we determine the URL of a
navigation_start event by finding a FrameLoader snapshot that precedes
it. However, we're seeing cases where we don't have a snapshot of the
FrameLoader with the new URL before the nav start event. This CL embeds
two essential piece of information for metric computation in the
navigationStart trace event itself so we don't have to look for
FrameLoader snapshots for them.

Bug:  824761 
Change-Id: I41ee17a58810a0d7b1fb918ceff215454d11c157
Reviewed-on: https://chromium-review.googlesource.com/975986
Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Deepanjan Roy <dproy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545421}
[modify] https://crrev.com/7d0fcf3dfdf86ce127391d431cbe028f09607da6/third_party/WebKit/Source/core/loader/DocumentLoadTiming.cpp
[modify] https://crrev.com/7d0fcf3dfdf86ce127391d431cbe028f09607da6/third_party/WebKit/Source/core/loader/DocumentLoadTiming.h

The following revision refers to this bug:
  https://chromium.googlesource.com/catapult/+/5d35a2c7122c1ac4a9a37e7743a19f628f25a38b

commit 5d35a2c7122c1ac4a9a37e7743a19f628f25a38b
Author: Deepanjan Roy <dproy@chromium.org>
Date: Mon Mar 26 16:39:58 2018

Get navigation info without using FrameLoader snapshots

We currently look for a FrameLoader snapshot starting at a
navigationStart event, but often we do not have the right snapshot
before navigationStart. This CL reads the data directly from
navigationStart event if available.

A related chromium CL adds this data to the navigation_start trace
event.

Bug:  chromium:824761 

Change-Id: I3c73307d79f1c4f308a29f049c6286f00dd59ffe
Reviewed-on: https://chromium-review.googlesource.com/968942
Commit-Queue: Deepanjan Roy <dproy@chromium.org>
Reviewed-by: Ben Hayden <benjhayden@chromium.org>

[modify] https://crrev.com/5d35a2c7122c1ac4a9a37e7743a19f628f25a38b/tracing/tracing/importer/find_load_expectations.html
[modify] https://crrev.com/5d35a2c7122c1ac4a9a37e7743a19f628f25a38b/tracing/tracing/metrics/system_health/loading_metric_test.html

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/13822b93deb44b969f5aa180d18f75ea81b28b31

commit 13822b93deb44b969f5aa180d18f75ea81b28b31
Author: catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Tue Mar 27 03:32:28 2018

Roll src/third_party/catapult/ bffbf166f..767f070f1 (6 commits)

https://chromium.googlesource.com/catapult.git/+log/bffbf166f004..767f070f1df4

$ git log bffbf166f..767f070f1 --date=short --no-merges --format='%ad %ae %s'
2018-03-26 eakuefner [Telemetry] Add more diagnostics to benchmark_total_duration
2018-03-26 dtu [pinpoint] Add descriptions to try job dialogs.
2018-03-22 laszio [Telemetry] include story tags in benchmark_runner list
2018-03-26 dproy Get navigation info without using FrameLoader snapshots
2018-03-26 nednguyen Supress Telemetry pylint error
2018-03-26 eakuefner Revert "HistogramSet - Only merge histograms with stories."

Created with:
  roll-dep src/third_party/catapult
BUG= chromium:819969 , chromium:824761 , chromium:819969 


The AutoRoll server is located here: https://catapult-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=sullivan@chromium.org

Change-Id: I9b5458944cce2430a96f4d92854bed716b4b23ed
Reviewed-on: https://chromium-review.googlesource.com/981594
Reviewed-by: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#545975}
[modify] https://crrev.com/13822b93deb44b969f5aa180d18f75ea81b28b31/DEPS