[TTS] Add server control from a field_trial param.

chrome/browser/android/contextualsearch/contextual_search_field_trial.h

Index: chrome/browser/android/contextualsearch/contextual_search_field_trial.h
diff --git a/chrome/browser/android/contextualsearch/contextual_search_field_trial.h b/chrome/browser/android/contextualsearch/contextual_search_field_trial.h
index bcaa594b687840a172ab3ef5c9e5d68dbbbac83f..fc99a551e0be2cc7c7d49160daeaf5e63e6216d3 100644
--- a/chrome/browser/android/contextualsearch/contextual_search_field_trial.h
+++ b/chrome/browser/android/contextualsearch/contextual_search_field_trial.h
@@ -38,6 +38,10 @@ class ContextualSearchFieldTrial {
   // Gets whether Bar integration with Contextual Cards data is enabled.
   bool IsContextualCardsBarIntegrationEnabled();
 
+  // Gets an explicit version to use for Contextual Cards integration, or 0 if
+  // not set.
+  int GetContextualCardsVersion();
+
   // Disables the cache.
   void DisableCache();
 
@@ -74,17 +78,25 @@ class ContextualSearchFieldTrial {
   // Cached values.
   bool is_resolver_url_prefix_cached_;
   std::string resolver_url_prefix_;
+
   bool is_surrounding_size_cached_;
   int surrounding_size_;
+
   bool is_icing_surrounding_size_cached_;
   int icing_surrounding_size_;
+
   bool is_send_base_page_url_disabled_cached_;
   bool is_send_base_page_url_disabled_;
+
   bool is_decode_mentions_disabled_cached_;
   bool is_decode_mentions_disabled_;
+
   bool is_contextual_cards_bar_integration_enabled_cached_;
   bool is_contextual_cards_bar_integration_enabled_;
 
+  bool is_contextual_cards_version_cached_;
+  int contextual_cards_version_;
+
   DISALLOW_COPY_AND_ASSIGN(ContextualSearchFieldTrial);
 };