[Reland] Improve the resolution of the menu item homescreen launch source metric.

[Reland] Improve the resolution of the menu item homescreen launch source metric.

This CL deprecates the SOURCE_ADD_TO_HOMESCREEN source for homescreen
launch intents on Android. Three new buckets are added in its place:
SOURCE_ADD_TO_HOMESCREEN_PWA, SOURCE_ADD_TO_HOMESCREEN_STANDALONE, and
SOURCE_ADD_TO_HOMESCREEN_SHORTCUT.

Existing shortcuts are mapped to either the STANDALONE or SHORTCUT
sources, as it is impossible to properly distinguish PWAs from non-PWAs
when added from the menu item prior to this CL. Following this CL, PWAs
added from the menu item are explicitly tagged with
SOURCE_ADD_TO_HOMESCREEN_PWA.

This is a reland on M57 branch as the earlier merge inadvertently brought
an M57-incompatible change along with it.

BUG=690266
Review-Url: https://codereview.chromium.org/2697473005
Cr-Commit-Position: refs/heads/master@{#450902}
(cherry picked from commit de938a8e39930cca0d2a1f8c96f2cdc9b15192de)

Review-Url: https://codereview.chromium.org/2709613002 .
Cr-Commit-Position: refs/branch-heads/2987@{#601}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/086340785581c211b9647370d63b609aed5c5a76

[dominickn, 2017-02-20 23:08:02]

Description was changed from

==========
[Reland] Improve the resolution of the menu item homescreen launch source
metric.

This CL deprecates the SOURCE_ADD_TO_HOMESCREEN source for homescreen
launch intents on Android. Three new buckets are added in its place:
SOURCE_ADD_TO_HOMESCREEN_PWA, SOURCE_ADD_TO_HOMESCREEN_STANDALONE, and
SOURCE_ADD_TO_HOMESCREEN_SHORTCUT.

Existing shortcuts are mapped to either the STANDALONE or SHORTCUT
sources, as it is impossible to properly distinguish PWAs from non-PWAs
when added from the menu item prior to this CL. Following this CL, PWAs
added from the menu item are explicitly tagged with
SOURCE_ADD_TO_HOMESCREEN_PWA.

This is a reland on M57 branch as the earlier merge inadvertently brought
an M57-incompatible change along with it.

BUG=690266

Review-Url: https://codereview.chromium.org/2697473005
Cr-Commit-Position: refs/heads/master@{#450902}
(cherry picked from commit de938a8e39930cca0d2a1f8c96f2cdc9b15192de)
==========

to

==========
[Reland] Improve the resolution of the menu item homescreen launch source
metric.

This CL deprecates the SOURCE_ADD_TO_HOMESCREEN source for homescreen
launch intents on Android. Three new buckets are added in its place:
SOURCE_ADD_TO_HOMESCREEN_PWA, SOURCE_ADD_TO_HOMESCREEN_STANDALONE, and
SOURCE_ADD_TO_HOMESCREEN_SHORTCUT.

Existing shortcuts are mapped to either the STANDALONE or SHORTCUT
sources, as it is impossible to properly distinguish PWAs from non-PWAs
when added from the menu item prior to this CL. Following this CL, PWAs
added from the menu item are explicitly tagged with
SOURCE_ADD_TO_HOMESCREEN_PWA.

This is a reland on M57 branch as the earlier merge inadvertently brought
an M57-incompatible change along with it.

BUG=690266

Review-Url: https://codereview.chromium.org/2697473005
Cr-Commit-Position: refs/heads/master@{#450902}
(cherry picked from commit de938a8e39930cca0d2a1f8c96f2cdc9b15192de)

Review-Url: https://codereview.chromium.org/2709613002 .
Cr-Commit-Position: refs/branch-heads/2987@{#601}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/086340785581c211b9647370d63b...
==========

[dominickn, 2017-02-20 23:08:07]

Committed patchset #1 (id:1) manually as
086340785581c211b9647370d63b609aed5c5a76.