[translate] Add ranker model proto and loader.

components/translate/core/browser/BUILD.gn

Index: components/translate/core/browser/BUILD.gn
diff --git a/components/translate/core/browser/BUILD.gn b/components/translate/core/browser/BUILD.gn
index fc31a04facd4c73ac78743f13b9612baba5e77d9..01d219863f5b0e1168d0449d1146becd4b19d682 100644
--- a/components/translate/core/browser/BUILD.gn
+++ b/components/translate/core/browser/BUILD.gn
@@ -11,6 +11,10 @@ static_library("browser") {
     "language_state.cc",
     "language_state.h",
     "page_translated_details.h",
+    "ranker_model.cc",
+    "ranker_model.h",
+    "ranker_model_loader.cc",
+    "ranker_model_loader.h",
     "translate_accept_languages.cc",
     "translate_accept_languages.h",
     "translate_browser_metrics.cc",
@@ -90,6 +94,8 @@ source_set("unit_tests") {
     "language_state_unittest.cc",
     "mock_translate_driver.cc",
     "mock_translate_driver.h",
+    "ranker_model_loader_unittest.cc",
+    "ranker_model_unittest.cc",
     "translate_browser_metrics_unittest.cc",
     "translate_language_list_unittest.cc",
     "translate_manager_unittest.cc",