Add timer

Author: schmidt-sebastian

firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLiteSchema.java

@@ -97,6 +97,7 @@ void runSchemaUpgrades(int fromVersion) {
    *     otherwise for testing.
    */
   void runSchemaUpgrades(int fromVersion, int toVersion) {
+    long startTime = System.currentTimeMillis();
     /*
      * New migrations should be added at the end of the series of `if` statements and should follow
      * the pattern. Make sure to increment `VERSION` and to read the comment below about
@@ -199,6 +200,13 @@ void runSchemaUpgrades(int fromVersion, int toVersion) {
       Preconditions.checkState(Persistence.INDEXING_SUPPORT_ENABLED);
       createFieldIndex();
     }
+
+    Logger.debug(
+        "SQLiteSchema",
+        "Migration from version %s to %s took %s milliseconds",
+        fromVersion,
+        toVersion,
+        System.currentTimeMillis() - startTime);
   }
 
   /**