The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e48879debd5fc75f6dfdec745922dbc0c5846400

commit e48879debd5fc75f6dfdec745922dbc0c5846400
Author: Dominick Ng <dominickn@chromium.org>
Date: Thu Jan 18 07:25:57 2018

Implement the Webapp.Install.InstallEvent metric.

This metric is the first of the revamped Installability metrics to be
implemented. It is intended to replace Webapp.Install.InstallSource and
WebApk.Install.InstallSource as the canonical metric of installation
sources for PWAs installed on desktop and Android.

The new metric has 7 buckets, differentiating between installations
triggered by:
 - the menu item
 - automatic prompts (i.e. app banners without beforeinstallpromptevent)
 - developer-triggered prompts (i.e.  beforeinstallpromptevent.prompt())
 - in debug mode via devtools or the bypass checks flag

And between installations triggered from:
 - a browser tab
 - a Chrome Custom Tab (Android only)

This bucketing sums to the total number of installations, and should be
future-proof as no further segmentation of these buckets is expected.

This CL adds tests for the recording of the install source, and also
renames WebAppInstallSource to WebappInstallSource for consistency with
the "Webapp" naming convention.

BUG= 800991 

Change-Id: I4131ade3829536ff328c2bbdf62b1a75910785e8
Reviewed-on: https://chromium-review.googlesource.com/863148
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Matt Giuca <mgiuca@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530083}
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/android/javatests/src/org/chromium/chrome/browser/banners/AppBannerManagerTest.java
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/android/webapk/webapk_install_service.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/android/webapk/webapk_install_service.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/android/webapk/webapk_metrics.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/android/webapk/webapk_metrics.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/android/webapps/add_to_homescreen_manager.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_infobar_delegate_android.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_infobar_delegate_android.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager_android.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager_android.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager_browsertest.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager_desktop.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/banners/app_banner_manager_desktop.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/extensions/api/management/chrome_management_api_delegate.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/extensions/bookmark_app_helper.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/extensions/bookmark_app_helper.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/extensions/bookmark_app_helper_browsertest.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/extensions/bookmark_app_helper_unittest.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/extensions/tab_helper.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/installable/installable_metrics.cc
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/chrome/browser/installable/installable_metrics.h
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/e48879debd5fc75f6dfdec745922dbc0c5846400/tools/metrics/histograms/histograms.xml