Gonzalo has a CL out for review for this at https://codereview.chromium.org/2632693002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/63066a0f4c6ac09670cac21748cc88f3bc14a36a

commit 63066a0f4c6ac09670cac21748cc88f3bc14a36a
Author: gonzalon <gonzalon@chromium.org>
Date: Tue Jan 31 15:08:20 2017

The method WebappRegistry#isWebApkInstalled now reuses InstallerDelegate#isInstalled so as not to repeat code.

BUG= 639428 

Review-Url: https://codereview.chromium.org/2632693002
Cr-Commit-Position: refs/heads/master@{#447233}

[modify] https://crrev.com/63066a0f4c6ac09670cac21748cc88f3bc14a36a/chrome/android/java/src/org/chromium/chrome/browser/banners/InstallerDelegate.java
[modify] https://crrev.com/63066a0f4c6ac09670cac21748cc88f3bc14a36a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
[modify] https://crrev.com/63066a0f4c6ac09670cac21748cc88f3bc14a36a/chrome/android/javatests/src/org/chromium/chrome/browser/banners/AppBannerManagerTest.java
[modify] https://crrev.com/63066a0f4c6ac09670cac21748cc88f3bc14a36a/chrome/android/javatests/src/org/chromium/chrome/browser/banners/InstallerDelegateTest.java