Add flag guard for the NO_POS introduction.

This CL adds a flag that controls whether to use NO_POS as default POS of Japanese Personal Dictionary or not. This CL also re-implement special treatment of SUGGESTION_ONLY, which is planned to be removed after successful launch.

PiperOrigin-RevId: 579750421

src/dictionary/user_dictionary.cc

@@ -161,6 +161,8 @@ class UserDictionary::TokensIndex {
       if (!dic.enabled() || dic.entries_size() == 0) {
         continue;
       }
+      const bool is_android_shortcuts =
+          (dic.name() == "__auto_imported_android_shortcuts_dictionary");
 
       for (const UserDictionaryStorage::UserDictionaryEntry &entry :
            dic.entries()) {
@@ -215,6 +217,13 @@ class UserDictionary::TokensIndex {
               absl::StripAsciiWhitespace(entry.comment());
           for (auto &token : tokens) {
             strings::Assign(token.comment, comment);
+            if (is_android_shortcuts &&
+                token.has_attribute(UserPos::Token::SUGGESTION_ONLY)) {
+              // TODO(b/295964970): This special implementation is planned to be
+              // removed after validating the safety of NO_POS implementation.
+              token.remove_attribute(UserPos::Token::SUGGESTION_ONLY);
+              token.add_attribute(UserPos::Token::SHORTCUT);
+            }
             user_pos_tokens_.push_back(std::move(token));
           }
         }

src/dictionary/user_dictionary_test.cc

@@ -541,7 +541,7 @@ TEST_F(UserDictionaryTest, TestLookupWithShortCut) {
     entry->set_value("noun");
     entry->set_pos(user_dictionary::UserDictionary::NOUN);
 
-    // SUGGESTION ONLY word is not handled as SHORTCUT word.
+    // SUGGESTION ONLY word is handled as SHORTCUT word.
     entry = dic->add_entries();
     entry->set_key("key");
     entry->set_value("suggest_only");
@@ -565,6 +565,7 @@ TEST_F(UserDictionaryTest, TestLookupWithShortCut) {
   const Entry kExpected2[] = {
       {"key", "noun", kNounId, kNounId},
       {"key", "no_pos", kUnknownId, kUnknownId},
+      {"key", "suggest_only", kUnknownId, kUnknownId},
   };
   const Entry kExpectedPrediction[] = {
       {"key", "noun", kNounId, kNounId},