Adding warmup call API for Settings search ranking.

- This allows the ranking implementations to prepare for predictions and
avoids latency on the first prediction call.

Bug: 38197948
Bug: 37312700

Test: RunSettingsRoboTests

Change-Id: I1878b14765ad7cede5648fa1c7f29c419c2e5535

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

@@ -130,4 +130,10 @@ public interface SearchFeatureProvider {
         return false;
     }
 
+    /**
+     * Prepare for search ranking predictions to avoid latency on the first prediction call.
+     */
+    default void searchRankingWarmup(Context context) {
+    }
+
 }

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

@@ -209,6 +209,10 @@ public class SearchFragment extends InstrumentedFragment implements SearchView.O
     @Override
     public void onResume() {
         super.onResume();
+        Context appContext = getContext().getApplicationContext();
+        if (mSearchFeatureProvider.isSmartSearchRankingEnabled(appContext)) {
+            mSearchFeatureProvider.searchRankingWarmup(appContext);
+        }
         requery();
     }