Can someone provide more details on the problems with unpredictability?

The 10 second thing was designed to prevent sites that people click on and then immediately move away from earning engagement.

ojan has been asking for this for a while. There are a few reasons:

1. the 10 second delay means that developers can't really reason about when they'll earn engagement. This has been an ancillary problem for existing usage (when will an app banner appear? When will I be granted durable storage?), but is a real problem for any usage of site engagement as a filter for web platform features.

2. as currently implemented, the 10 second delay is from when the navigation is committed, not when the page is ready to interact with. That means that on slower connections, the 10 second delay might have already expired by the time the page has anything to interact with
  - as a subpoint, firing off the delay on the load event or some other point in the navigation would make it more effective for its original purpose, but at the cost of making it more difficult to test

3. engagement now decays much more quickly than when the 10 second delay was first introduced, mitigating the effect of earning engagement more quickly. Right now, removing the delay mans a site will earn at most +0.6 engagement more than they otherwise would have with the delay in place (assuming that the user is clicking on the site some time in the first 10 seconds before moving away).

Thanks for the explanation!

I'm not really sold on point 1, and worry that making predictability too much of a priority we might lost freedom to make engagement a better heuristic, but I agree that given points 2 and 3 this particular detail isn't adding any value.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5ae55b8c8ed39e3a1019afba988b5df208f53420

commit 5ae55b8c8ed39e3a1019afba988b5df208f53420
Author: dominickn <dominickn@chromium.org>
Date: Wed Feb 22 09:00:01 2017

Remove the 10 second delay before user input generates engagement.

The site engagement service currently waits 10 seconds after
navigation completes before allowing user input to generate engagement.
This reduces the predictability of the service. Engagement also decays
much more quickly now, meaning that the additional engagement earned
when removing the 10 second wait is negligible.

This CL instead allows engagement to be earned from the moment that the
page finishes loading.

BUG= 692878 

Review-Url: https://codereview.chromium.org/2693403003
Cr-Commit-Position: refs/heads/master@{#451942}

[modify] https://crrev.com/5ae55b8c8ed39e3a1019afba988b5df208f53420/chrome/browser/engagement/site_engagement_helper.cc
[modify] https://crrev.com/5ae55b8c8ed39e3a1019afba988b5df208f53420/chrome/browser/engagement/site_engagement_helper.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/14a17fb865e7f8925ad4f96ad0a810fb83056c1b

commit 14a17fb865e7f8925ad4f96ad0a810fb83056c1b
Author: dominickn <dominickn@chromium.org>
Date: Mon Apr 03 03:24:55 2017

Revert of Remove the 10 second delay before user input generates engagement. (patchset #1 id:1 of https://codereview.chromium.org/2693403003/ )

Reason for revert:
This caused a perf regression ( crbug.com/699749 )

Original issue's description:
> Remove the 10 second delay before user input generates engagement.
>
> The site engagement service currently waits 10 seconds after
> navigation completes before allowing user input to generate engagement.
> This reduces the predictability of the service. Engagement also decays
> much more quickly now, meaning that the additional engagement earned
> when removing the 10 second wait is negligible.
>
> This CL instead allows engagement to be earned from the moment that the
> page finishes loading.
>
> BUG= 692878 
>
> Review-Url: https://codereview.chromium.org/2693403003
> Cr-Commit-Position: refs/heads/master@{#451942}
> Committed: https://chromium.googlesource.com/chromium/src/+/5ae55b8c8ed39e3a1019afba988b5df208f53420

TBR=benwells@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG= 692878 

Review-Url: https://codereview.chromium.org/2793863002
Cr-Commit-Position: refs/heads/master@{#461365}

[modify] https://crrev.com/14a17fb865e7f8925ad4f96ad0a810fb83056c1b/chrome/browser/engagement/site_engagement_helper.cc
[modify] https://crrev.com/14a17fb865e7f8925ad4f96ad0a810fb83056c1b/chrome/browser/engagement/site_engagement_helper.h

I'd like to merge the revert in c#6 to M58. This addresses a perf regression. The old behaviour has been the standard for many milestones so it should be very safe.

This bug requires manual review: Reverts referenced in bugdroid comments after merge request.
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), bhthompson@(ChromeOS), govind@(Desktop)

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

Approved for M58 branch 3029.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/65a8e700a0932bae679ae2f800c31570d9545725

commit 65a8e700a0932bae679ae2f800c31570d9545725
Author: Ben Wells <benwells@chromium.org>
Date: Thu Apr 06 00:22:18 2017

Revert of Remove the 10 second delay before user input generates engagement. (patchset #1 id:1 of https://codereview.chromium.org/2693403003/ )

Reason for revert:
This caused a perf regression ( crbug.com/699749 )

Original issue's description:
> Remove the 10 second delay before user input generates engagement.
>
> The site engagement service currently waits 10 seconds after
> navigation completes before allowing user input to generate engagement.
> This reduces the predictability of the service. Engagement also decays
> much more quickly now, meaning that the additional engagement earned
> when removing the 10 second wait is negligible.
>
> This CL instead allows engagement to be earned from the moment that the
> page finishes loading.
>
> BUG= 692878 
>
> Review-Url: https://codereview.chromium.org/2693403003
> Cr-Commit-Position: refs/heads/master@{#451942}
> Committed: https://chromium.googlesource.com/chromium/src/+/5ae55b8c8ed39e3a1019afba988b5df208f53420

TBR=benwells@chromium.org
BUG= 692878 

Review-Url: https://codereview.chromium.org/2793863002
Cr-Commit-Position: refs/heads/master@{#461365}
(cherry picked from commit 14a17fb865e7f8925ad4f96ad0a810fb83056c1b)

Review-Url: https://codereview.chromium.org/2801803003 .
Cr-Commit-Position: refs/branch-heads/3029@{#599}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}

[modify] https://crrev.com/65a8e700a0932bae679ae2f800c31570d9545725/chrome/browser/engagement/site_engagement_helper.cc
[modify] https://crrev.com/65a8e700a0932bae679ae2f800c31570d9545725/chrome/browser/engagement/site_engagement_helper.h

Going to leave this one alone for now.