The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/118fee6c362144aaf3fb5672556a6a849a8560f6

commit 118fee6c362144aaf3fb5672556a6a849a8560f6
Author: Justin Cohen <justincohen@google.com>
Date: Thu Dec 06 19:36:59 2018

[ios] Add more metrics to iOS preload controller.

Add histograms to track last committed index, time from
prerender creation to release, and if it's from an NTP.

Bug:  911763 
Change-Id: I3bfa423a8cb916f18002f0b6b25ba4f4b56eafa6
Reviewed-on: https://chromium-review.googlesource.com/c/1361637
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614450}
[modify] https://crrev.com/118fee6c362144aaf3fb5672556a6a849a8560f6/ios/chrome/browser/prerender/preload_controller.mm
[modify] https://crrev.com/118fee6c362144aaf3fb5672556a6a849a8560f6/ios/chrome/browser/ui/browser_view_controller.mm
[modify] https://crrev.com/118fee6c362144aaf3fb5672556a6a849a8560f6/tools/metrics/histograms/histograms.xml

[Auto-generated comment by a script] We noticed that this issue is targeted for M-72; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-72 label, otherwise remove Merge-TBD label. Thanks.

Verified on TOT, I see the following in chrome://histograms
Prerender.PrerenderLoadedOnFirstNTP 
Prerender.PrerenderLoadedOnIndex 
Prerender.PrerenderStartToReleaseContentsTime

Your change meets the bar and is auto-approved for M72. Please go ahead and merge the CL to branch 3626 manually. Please contact milestone owner if you have questions.
Owners: govind@(Android), kariahda@(iOS), djmm@(ChromeOS), abdulsyed@(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/+/a0900dd0fd1f590299059203759481181b2e35e5

commit a0900dd0fd1f590299059203759481181b2e35e5
Author: Justin Cohen <justincohen@google.com>
Date: Fri Dec 07 22:06:58 2018

[ios] Add more metrics to iOS preload controller.

Add histograms to track last committed index, time from
prerender creation to release, and if it's from an NTP.

Bug:  911763 
Change-Id: I3bfa423a8cb916f18002f0b6b25ba4f4b56eafa6
Reviewed-on: https://chromium-review.googlesource.com/c/1361637
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#614450}(cherry picked from commit 118fee6c362144aaf3fb5672556a6a849a8560f6)
Reviewed-on: https://chromium-review.googlesource.com/c/1368670
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/branch-heads/3626@{#154}
Cr-Branched-From: d897fb137fbaaa9355c0c93124cc048824eb1e65-refs/heads/master@{#612437}
[modify] https://crrev.com/a0900dd0fd1f590299059203759481181b2e35e5/ios/chrome/browser/prerender/preload_controller.mm
[modify] https://crrev.com/a0900dd0fd1f590299059203759481181b2e35e5/ios/chrome/browser/ui/browser_view_controller.mm
[modify] https://crrev.com/a0900dd0fd1f590299059203759481181b2e35e5/tools/metrics/histograms/histograms.xml

Verified the histograms on about://histograms.
Prerender.PrerenderLoadedOnFirstNTP 
Prerender.PrerenderLoadedOnIndex 
Prerender.PrerenderStartToReleaseContentsTime

Verified on M72.0.3626.15 beta
iOS: 12.1.1, iPad Pro.

The following revision refers to this bug: 
https://chromium.googlesource.com/chromium/src.git/+/a0900dd0fd1f590299059203759481181b2e35e5

Commit: a0900dd0fd1f590299059203759481181b2e35e5
Author: justincohen@google.com
Commiter: justincohen@chromium.org
Date: 2018-12-07 22:06:58 +0000 UTC

[ios] Add more metrics to iOS preload controller.

Add histograms to track last committed index, time from
prerender creation to release, and if it's from an NTP.

Bug:  911763 
Change-Id: I3bfa423a8cb916f18002f0b6b25ba4f4b56eafa6
Reviewed-on: https://chromium-review.googlesource.com/c/1361637
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#614450}(cherry picked from commit 118fee6c362144aaf3fb5672556a6a849a8560f6)
Reviewed-on: https://chromium-review.googlesource.com/c/1368670
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/branch-heads/3626@{#154}
Cr-Branched-From: d897fb137fbaaa9355c0c93124cc048824eb1e65-refs/heads/master@{#612437}