The plan is to roll this out using Finch, work out what the right engagement levels are for triggering banners, then complete the rollout and delete all of the content-settings visit event code.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cd25e0bc03cbe4f606646d4ca7b95000de0fc055

commit cd25e0bc03cbe4f606646d4ca7b95000de0fc055
Author: dominickn <dominickn@chromium.org>
Date: Fri Jun 10 04:45:22 2016

Construct the site engagement helper with a site engagement service.

This CL refactors the site engagement helper to initialise its site
engagement service point at construction. This obviates the
need to query for the site engagement service each time
engagement is increased. The service' private interface is also
refactored to take a WebContents pointer rather than a GURL
on engagement increases, allowing it to signal other observers
of the WebContents in a future CL.

BUG= 616322 

Review-Url: https://codereview.chromium.org/2042243004
Cr-Commit-Position: refs/heads/master@{#399101}

[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_helper.cc
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_helper.h
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_service.cc
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_service.h
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_service_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cd25e0bc03cbe4f606646d4ca7b95000de0fc055

commit cd25e0bc03cbe4f606646d4ca7b95000de0fc055
Author: dominickn <dominickn@chromium.org>
Date: Fri Jun 10 04:45:22 2016

Construct the site engagement helper with a site engagement service.

This CL refactors the site engagement helper to initialise its site
engagement service point at construction. This obviates the
need to query for the site engagement service each time
engagement is increased. The service' private interface is also
refactored to take a WebContents pointer rather than a GURL
on engagement increases, allowing it to signal other observers
of the WebContents in a future CL.

BUG= 616322 

Review-Url: https://codereview.chromium.org/2042243004
Cr-Commit-Position: refs/heads/master@{#399101}

[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_helper.cc
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_helper.h
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_service.cc
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_service.h
[modify] https://crrev.com/cd25e0bc03cbe4f606646d4ca7b95000de0fc055/chrome/browser/engagement/site_engagement_service_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ecc791758fba66a0906b9450780a23e898a44b63

commit ecc791758fba66a0906b9450780a23e898a44b63
Author: dominickn <dominickn@chromium.org>
Date: Wed Jun 29 05:04:24 2016

Allow app banners to be triggered by increases in site engagement.

This CL makes the app banner manager a site engagement observer. This
allows banners to be triggered when the engagement for a site reaches
a sufficient level, rather than being restricted to triggering on
navigations.

The experiment switch for enabling site engagement banners is moved back
into the AppBannerTriggering variation from the site engagement
variation, as site engagement has now launched to the stable channel.

A future CL will remove the existing navigation-based heuristic
entirely.

BUG= 616322 
TBR=sky@chromium.org

Review-Url: https://codereview.chromium.org/2024953005
Cr-Commit-Position: refs/heads/master@{#402726}

[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/android/banners/app_banner_manager_android.cc
[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/banners/app_banner_manager.cc
[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/banners/app_banner_manager.h
[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/banners/app_banner_settings_helper.cc
[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/banners/app_banner_settings_helper.h
[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/banners/app_banner_settings_helper_unittest.cc
[modify] https://crrev.com/ecc791758fba66a0906b9450780a23e898a44b63/chrome/browser/ui/browser.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f9c4f230b41dd5372df376f43bb753bdf5989253

commit f9c4f230b41dd5372df376f43bb753bdf5989253
Author: dominickn <dominickn@chromium.org>
Date: Fri Aug 05 05:43:52 2016

Rename the app banner variations key for total site engagement score.

This change avoids a conflict between non-site engagement and site
engagement banner triggering whilst we are transitioning from the former
to the latter.

BUG= 616322 

Review-Url: https://codereview.chromium.org/2216073003
Cr-Commit-Position: refs/heads/master@{#409997}

[modify] https://crrev.com/f9c4f230b41dd5372df376f43bb753bdf5989253/chrome/browser/banners/app_banner_settings_helper.cc

Requesting merge of #6 to M53. It's a small key change to sync with a Finch experiment. Clients which have a mismatched wrong key fall back to a default value instead of getting it from the experiment, so it should be pretty safe to merge.

Your change meets the bar and is auto-approved for M53 (branch: 2785)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/31498da138c05bff551d963a0738ef3440c0b102

commit 31498da138c05bff551d963a0738ef3440c0b102
Author: Dominick Ng <dominickn@chromium.org>
Date: Tue Aug 09 01:33:43 2016

Rename the app banner variations key for total site engagement score.

This change avoids a conflict between non-site engagement and site
engagement banner triggering whilst we are transitioning from the former
to the latter.

BUG= 616322 

Review-Url: https://codereview.chromium.org/2216073003
Cr-Commit-Position: refs/heads/master@{#409997}
(cherry picked from commit f9c4f230b41dd5372df376f43bb753bdf5989253)

Review URL: https://codereview.chromium.org/2226133003 .

Cr-Commit-Position: refs/branch-heads/2785@{#539}
Cr-Branched-From: 68623971be0cfc492a2cb0427d7f478e7b214c24-refs/heads/master@{#403382}

[modify] https://crrev.com/31498da138c05bff551d963a0738ef3440c0b102/chrome/browser/banners/app_banner_settings_helper.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0a388886e07037d76be02dbf656cc1eb35bb681d

commit 0a388886e07037d76be02dbf656cc1eb35bb681d
Author: dominickn <dominickn@chromium.org>
Date: Thu Sep 15 05:09:47 2016

Allow app banners to trigger on 0 engagement.

BUG= 616322 

Review-Url: https://codereview.chromium.org/2344793002
Cr-Commit-Position: refs/heads/master@{#418787}

[modify] https://crrev.com/0a388886e07037d76be02dbf656cc1eb35bb681d/chrome/browser/banners/app_banner_manager.cc
[modify] https://crrev.com/0a388886e07037d76be02dbf656cc1eb35bb681d/chrome/browser/banners/app_banner_settings_helper.cc

This is now 100% rolled out. I'm going to begin the process of removing the code supporting the old navigation based heuristic for M57.