ServiceWorker: Add UMA for ServiceWorkerDatabase

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 5494219ea5da476ba91c8030c4f845612d27dab6..1d74711d07667e3f8b898a957ddfdd26b6b05422 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -23870,6 +23870,28 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="ServiceWorker.Database.OpenResult"
+    enum="ServiceWorkerDatabaseStatus">
+  <owner>nhiroki@chromium.org</owner>
+  <summary>
+    Records result of opening a database for ServiceWorkerDatabase.
+  </summary>
+</histogram>
+
+<histogram name="ServiceWorker.Database.ReadResult"
+    enum="ServiceWorkerDatabaseStatus">
+  <owner>nhiroki@chromium.org</owner>
+  <summary>Records result of read operations in ServiceWorkerDatabase.</summary>
+</histogram>
+
+<histogram name="ServiceWorker.Database.WriteResult"
+    enum="ServiceWorkerDatabaseStatus">
+  <owner>nhiroki@chromium.org</owner>
+  <summary>
+    Records result of write operations in ServiceWorkerDatabase.
+  </summary>
+</histogram>
+
 <histogram name="Settings.DefaultSearchProvider" enum="OmniboxSearchEngine">
   <obsolete>
     Deprecated in Chrome 30.  Use Search.DefaultSearchProviderType instead.
@@ -42101,6 +42123,15 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="10" label="SERVICE_UTILITY_SEMANTIC_CAPS_FAILED"/>
 </enum>
 
+<enum name="ServiceWorkerDatabaseStatus" type="int">
+  <int value="0" label="STATUS_OK"/>
+  <int value="1" label="STATUS_ERROR_NOT_FOUND"/>
+  <int value="2" label="STATUS_ERROR_IO_ERROR"/>
+  <int value="3" label="STATUS_ERROR_CORRUPTED"/>
+  <int value="4" label="STATUS_ERROR_FAILED"/>
+  <int value="5" label="STATUS_ERROR_MAX"/>
+</enum>
+
 <enum name="SessionStartupPref" type="int">
   <int value="0" label="Open home page (unused)"/>
   <int value="1" label="Continue from last opened pages"/>