Add UMA metric to track the time elapsed since a WebAPK was last launched

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
index c4d55b511995c8125fbede9e250d66319866d5ca..8ac103a43a77fdce6e7c04aecc4f4b3426ebc0d1 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
@@ -182,6 +182,14 @@ public class WebApkActivity extends WebappActivity {
         maybeShowDisclosure(storage);
     }
 
+    @Override
+    protected void onUpdatedLastUsedTime(
+            WebappDataStorage storage, boolean previouslyLaunched, long previousUsageTimestamp) {
+        if (previouslyLaunched) {
+            WebApkUma.recordLaunchInterval(storage.getLastUsedTime() - previousUsageTimestamp);
+        }
+    }
+
     /**
      * If we're showing a WebApk that's not with an expected package, it must be an
      * "Unbound WebApk" (crbug.com/714735) so show a notification that it's running in Chrome.