Friendly ping!

BTW the proposals 1 and 2 above are not exclusive: I would like both of them getting implemented.

I think it is better to create new histograms with clear names and descriptions. This will make obvious that the data is not comparable to the previous histograms.

Fitting Chrome Home metrics into the old framework is painful and difficult and would likely lead to confusion. 

Vitalii, thanks for the comment! Still, I think we do not understand each other:
 - this bug is not concerned about _metrics_ for CH
   (+markusheintz, is anyone following up on metrics for CH?)

 - this bug is about signals to UserClassifier and to RemoteSuggestionsScheduler. As the code stays the same for CH and non-CH, we need to unify the signals, at least to some extent.

Filed  issue 731128  for one of the OnNTPOpened issues

OnPageShown is currently called when the list of sections is reset: once on start and again if the list of categories changed, which should pretty much never happen in Chrome Home.

To raise how often it is called, what frequency of events would be right?
- Every time the bottom sheet is opened? (then we have the issue with it being used only for the omnibox)
- Every time the home tab is shown? It would trigger multiple times when switching apps, or between the various bottom sheet tabs.

You can look at some of the user actions from https://docs.google.com/spreadsheets/d/1I5-p_WCQJxVv-OK3BXyGQ9McjGsUOvr7Er454zzcqp0/edit#gid=1383506007 for one that would match the desired behaviour maybe. I guess one of the Android.ChromeHome.Opened or Suggestions.SurfaceVisible would work.

Thanks, Nicolas!

I think that the correct frequency for both OnPageShown() and OnNTPOpened() is "Every time the home tab is shown". Does it match the "Suggestions.SurfaceVisible" user action?

Could you possibly take care of that?

On a related note, RemoteSuggestionsScheduler::OnNTPOpened() should get renamed to RemoteSuggestionsScheduler::OnSuggestionsSurfaceOpened(). I will take care of that (later).

Suggestions.SurfaceVisible would be the right one indeed, and sure, I can take that.

Thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9fc3341ca5afc14bc3ab776a0718e53cce1d49a1

commit 9fc3341ca5afc14bc3ab776a0718e53cce1d49a1
Author: Nicolas Dossou-gbete <dgn@chromium.org>
Date: Tue Jun 13 08:58:44 2017

[Suggestions] OnSurfaceOpened: Always record the shown suggestions

When Chrome Home is enabled, we don't reload the content of the surface
when it's opened if the categories did not change. Because of that, we
we skipping recording the displayed categories and suggestions. That
skewed the metrics and the scheduler notifications.

BUG= 728997 

Change-Id: I3320a6ea2cd0c35c7d521ef34bdd41a5f103c2e1
Reviewed-on: https://chromium-review.googlesource.com/531027
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Nicolas Dossou-Gbété <dgn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478942}
[modify] https://crrev.com/9fc3341ca5afc14bc3ab776a0718e53cce1d49a1/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SectionList.java