ServiceWorker: Add UMA for ServiceWorkerDatabase

content/browser/service_worker/service_worker_database.h

Index: content/browser/service_worker/service_worker_database.h
diff --git a/content/browser/service_worker/service_worker_database.h b/content/browser/service_worker/service_worker_database.h
index 660b4c7b73e52e7995b07ec6052141429f0a3db6..bfd0828b9bc944ac71acf2129af5f0166acf2834 100644
--- a/content/browser/service_worker/service_worker_database.h
+++ b/content/browser/service_worker/service_worker_database.h
@@ -22,7 +22,6 @@
 namespace leveldb {
 class DB;
 class Env;
-class Status;
 class WriteBatch;
 }
 
@@ -39,11 +38,14 @@ class CONTENT_EXPORT ServiceWorkerDatabase {
   explicit ServiceWorkerDatabase(const base::FilePath& path);
   ~ServiceWorkerDatabase();
 
+  // Used in UMA. A new value must be appended only.
   enum Status {
     STATUS_OK,
     STATUS_ERROR_NOT_FOUND,
+    STATUS_ERROR_IO_ERROR,
     STATUS_ERROR_CORRUPTED,
     STATUS_ERROR_FAILED,
+    STATUS_ERROR_MAX,
   };
 
   struct CONTENT_EXPORT RegistrationData {
@@ -272,10 +274,7 @@ class CONTENT_EXPORT ServiceWorkerDatabase {
       leveldb::WriteBatch* batch);
 
   bool IsOpen();
-
-  void HandleError(
-      const tracked_objects::Location& from_here,
-      const leveldb::Status& status);
+  void Disable();
 
   base::FilePath path_;
   scoped_ptr<leveldb::Env> env_;