Implement the ability to get all notifications in Chromium.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index eee68bddd2c9f3cdca49a354ca83347e851f2f45..f930359ebfa57daf5bc98508cdfc81240f59e265 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -24310,6 +24310,15 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Notifications.Database.OpenAfterCorruptionResult"
+    enum="NotificationDatabaseStatus">
+  <owner>peter@chromium.org</owner>
+  <summary>
+    Records the result status codes of opening the Web Notification database
+    after it has been destroyed in response to data corruption.
+  </summary>
+</histogram>
+
 <histogram name="Notifications.Database.OpenResult"
     enum="NotificationDatabaseStatus">
   <owner>peter@chromium.org</owner>
@@ -24318,6 +24327,15 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Notifications.Database.ReadForServiceWorkerResult"
+    enum="NotificationDatabaseStatus">
+  <owner>peter@chromium.org</owner>
+  <summary>
+    Records the result status codes of reading data of all notifications
+    associated with a Service Worker from the Web Notification database.
+  </summary>
+</histogram>
+
 <histogram name="Notifications.Database.ReadResult"
     enum="NotificationDatabaseStatus">
   <owner>peter@chromium.org</owner>