Add LanguageModel, a keyed service that collects language info from CLD.

chrome/browser/translate/chrome_translate_client.h

Index: chrome/browser/translate/chrome_translate_client.h
diff --git a/chrome/browser/translate/chrome_translate_client.h b/chrome/browser/translate/chrome_translate_client.h
index cf4a3565eb83e966ab9c3f8b4ead42dfc7066570..f9e2e65e0f56520df897904a122b03e604e46774 100644
--- a/chrome/browser/translate/chrome_translate_client.h
+++ b/chrome/browser/translate/chrome_translate_client.h
@@ -11,6 +11,7 @@
 #include "base/macros.h"
 #include "chrome/browser/ui/translate/translate_bubble_model.h"
 #include "components/translate/content/browser/content_translate_driver.h"
+#include "components/translate/content/browser/language_model_observer.h"
 #include "components/translate/core/browser/translate_client.h"
 #include "components/translate/core/browser/translate_step.h"
 #include "components/translate/core/common/translate_errors.h"
@@ -120,6 +121,7 @@ class ChromeTranslateClient
                   translate::TranslateErrors::Type error_type);
 
   translate::ContentTranslateDriver translate_driver_;
+  translate::LanguageModelObserver language_model_observer_;
   std::unique_ptr<translate::TranslateManager> translate_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeTranslateClient);