The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6acc886fa17fb43c4d790cd110ddc74f4179b0a5

commit 6acc886fa17fb43c4d790cd110ddc74f4179b0a5
Author: Peter Kotwicz <pkotwicz@chromium.org>
Date: Tue Nov 07 06:56:00 2017

[Android WebAPK] Add UMA to count how often binding to WebApkService fails

Currently, if binding the WebApkService fails,
WebApkServiceClient#notifyNotification() does not show a notification (no
notification attributed to the WebAPK, no notification attributed to Chrome.)
crbug.com/779960 shows that binding to the WebApkService sometimes fails.
The UMA metric will help determine how often the binding fails. If it
occurs often, the behavior of WebApkServiceClient#notifyNotification()
should be improved

BUG= 780596 

Change-Id: I743c044cf8f2484aa04983c59d1653a63b75f104
Reviewed-on: https://chromium-review.googlesource.com/749901
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514416}
[modify] https://crrev.com/6acc886fa17fb43c4d790cd110ddc74f4179b0a5/chrome/android/java/src/org/chromium/chrome/browser/metrics/WebApkUma.java
[modify] https://crrev.com/6acc886fa17fb43c4d790cd110ddc74f4179b0a5/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkServiceClient.java
[modify] https://crrev.com/6acc886fa17fb43c4d790cd110ddc74f4179b0a5/tools/metrics/histograms/histograms.xml