Maybe something combined with UIType and package name?

Right now we only set Tab#AppAssociatedWith when we have a valid session which is not the case for WebAPKs, I think, but if we were to ensure that all WebAPK custom tabs have a session associated with them and a corresponding package name, we can distinguish between webapp vs webapk (non-Chrome package name vs Chrome package name).

Hrmm. Do we need a custom tabs sessions for this? How does the current mechanism work where a PWA bounces out to a CCT? Do herb tabs have a CCT-session (presumably not?)

Ran: something to pick up with when you're back
Please work with Yusuf/Piotr to sort out specifics. The basic idea though is to track usage time linked with PWA.

We don't really need a session and none of the Chrome generated CCTs have a session right now. We need it only if differentiating between who created the CCT will help us with something. We can use that in the context of WebApp vs WebAPK, for differentiating between the two, but there might be other ways to do so.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bbac322d926bf7745a32569b5a5c0c8bcfe90518

commit bbac322d926bf7745a32569b5a5c0c8bcfe90518
Author: Ran Ji <ranj@chromium.org>
Date: Fri Nov 17 17:49:48 2017

Log time spent in customtab for Webapp and WebApk

Add an extra to the intent that sent to CCT to indicate where it comes from.
Currently the extra is only set by Webapp/WebApk

Bug:  769728 
Change-Id: I38ddbf9a5e797e602513de098a890645419d90c3
Reviewed-on: https://chromium-review.googlesource.com/751302
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Commit-Queue: Ran Ji <ranj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517460}
[modify] https://crrev.com/bbac322d926bf7745a32569b5a5c0c8bcfe90518/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabActivity.java
[modify] https://crrev.com/bbac322d926bf7745a32569b5a5c0c8bcfe90518/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabIntentDataProvider.java
[modify] https://crrev.com/bbac322d926bf7745a32569b5a5c0c8bcfe90518/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
[modify] https://crrev.com/bbac322d926bf7745a32569b5a5c0c8bcfe90518/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappInterceptNavigationDelegate.java
[modify] https://crrev.com/bbac322d926bf7745a32569b5a5c0c8bcfe90518/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappTabDelegate.java
[modify] https://crrev.com/bbac322d926bf7745a32569b5a5c0c8bcfe90518/tools/metrics/histograms/histograms.xml