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..cf027569a97d7195652d9b259ccc2421e00e7ab2 100644
--- a/chrome/browser/translate/chrome_translate_client.h
+++ b/chrome/browser/translate/chrome_translate_client.h
@@ -29,6 +29,7 @@ class ScopedCLDDynamicDataHarness;
 class PrefService;
 
 namespace translate {
+class LanguageModel;
 class LanguageState;
 class TranslateAcceptLanguages;
 class TranslatePrefs;
@@ -122,6 +123,10 @@ class ChromeTranslateClient
   translate::ContentTranslateDriver translate_driver_;
   std::unique_ptr<translate::TranslateManager> translate_manager_;
 
+  // Model to be notified about detected language of every page visited. Not
+  // owned here.
+  translate::LanguageModel* language_model_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeTranslateClient);
 };