Do not apply typing correction when the score is not enough.

when score < 0, literal-on-top is triggered, so better not to show
the history candidate at the top.

PiperOrigin-RevId: 650146088

src/prediction/user_history_predictor.cc

@@ -1432,7 +1432,10 @@ void UserHistoryPredictor::GetResultsFromHistoryDictionary(
     // Since dic_ is sorted in LRU, typing corrected queries are ranked lower
     // than the original key.
     for (const auto &c : corrected) {
-      if (LookupEntry(request_type, c.correction, c.correction, nullptr,
+      // Only apply when score > 0. When score < 0, we trigger literal-on-top
+      // in dictionary predictor.
+      if (c.score > 0.0 &&
+          LookupEntry(request_type, c.correction, c.correction, nullptr,
                       &(elm.value), prev_entry, results)) {
         break;
       }

src/prediction/user_history_predictor_test.cc

@@ -4408,7 +4408,7 @@ TEST_F(UserHistoryPredictorTest, TypingCorrection) {
   std::vector<TypeCorrectedQuery> expected;
   auto add_expected = [&](const std::string &key) {
     expected.emplace_back(
-        TypeCorrectedQuery{key, TypeCorrectedQuery::CORRECTION});
+        TypeCorrectedQuery{key, TypeCorrectedQuery::CORRECTION, 1.0});
   };
 
   // かつこ -> がっこ and かっこ