Add Yahoo answer to default engine metric

Author: DJAndries

browser/search_engines/search_engine_tracker.cc

@@ -52,6 +52,9 @@ SearchEngineP3A GetSearchEngineProvider(const GURL& search_engine_url,
     result = SearchEngineP3A::kDaum;
   } else if (type == SEARCH_ENGINE_NAVER) {
     result = SearchEngineP3A::kNaver;
+  } else if (type == SEARCH_ENGINE_YAHOO &&
+             search_engine_url.host_piece().ends_with(".jp")) {
+    result = SearchEngineP3A::kYahooJP;
   } else if (type == SEARCH_ENGINE_BRAVE) {
     result = SearchEngineP3A::kBrave;
   } else if (type == SEARCH_ENGINE_OTHER) {

browser/search_engines/search_engine_tracker.h

@@ -50,7 +50,8 @@ enum class SearchEngineP3A {
   kBrave,
   kDaum,
   kNaver,
-  kMaxValue = kNaver,
+  kYahooJP,
+  kMaxValue = kYahooJP,
 };
 
 // Note: append-only enumeration! Never remove any existing values, as this enum