Update Settings search result unique ids

- SearchResult stableIds are now DocIds from the database
- DocIds are data reference key's hash, when the key is not
empty or null
- Otherwise, DocIds are a hashcode from a set of fields.

Change-Id: Id36f7bf4ceaaa3a2bd326ecafbfe97fd0b247df2
Fixes: 37327194
Test: make RunSettingsRoboTest

src/com/android/settings/search/DatabaseIndexingManager.java

@@ -1061,10 +1061,11 @@ public class DatabaseIndexingManager {
          * Returns the doc id for this row.
          */
         public int getDocId() {
-            // The DocID should contains more than the title string itself (you may have two
-            // settings with the same title). So we need to use a combination of multiple
-            // attributes from this row.
-            return Objects.hash(updatedTitle, screenTitle, key, payloadType);
+            // Eventually we want all DocIds to be the data_reference key. For settings values,
+            // this will be preference keys, and for non-settings they should be unique.
+            return TextUtils.isEmpty(key)
+                    ? Objects.hash(updatedTitle, className, screenTitle, intentTargetClass)
+                    : key.hashCode();
         }
 
         public static class Builder {