The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8b15ff539fbbc48f1b9bf9e2d6ce378cff20e5f4

commit 8b15ff539fbbc48f1b9bf9e2d6ce378cff20e5f4
Author: pkotwicz <pkotwicz@chromium.org>
Date: Thu Nov 03 01:08:48 2016

Exclude the "WebAPK launcher Activity" from recents.

When a WebAPK is launched from the app list, it launches MainActivity which
sends an intent to WebappLauncherActivity. This CL excludes MainActivity from
Android Recents.

BUG= 661726 

Review-Url: https://codereview.chromium.org/2471913002
Cr-Commit-Position: refs/heads/master@{#429495}

[modify] https://crrev.com/8b15ff539fbbc48f1b9bf9e2d6ce378cff20e5f4/chrome/android/webapk/shell_apk/AndroidManifest.xml

Test steps:

1) On a Kitkat device, uninstall any currently installed "test WebAPKs" (APKs with yellow hexagon)
2) Enable WebAPKs by following steps in https://docs.google.com/a/google.com/document/d/1gHZ1YXO7QRZO6hgt11uqItNpl5WrZBJYxPYAnuJphXU/edit?usp=sharing
3) "Force Stop" Chrome
4) In Chrome for Android, navigate to https://goo.gl/36GSsH
5) Select "Add to Home screen" from the app menu. An infobar will show briefly. Press the "Install" button when asked to install the "Simple Test" APK
6) Close any running apps by swiping them away in "Android Recents"
7) Launch the newly created APK.
8) Go to "Android Recents"
9) Check that there is only one entry in "Android Recents"