[LanguageModel] Clear the model when clearing full history

components/translate/core/browser/language_model.cc

Index: components/translate/core/browser/language_model.cc
diff --git a/components/translate/core/browser/language_model.cc b/components/translate/core/browser/language_model.cc
index 6c575499ed3f12cbcce8ee10fd5e2b9fe31da825..6899b3872e80ff7dc35ffd6c13cbc0973c00d901 100644
--- a/components/translate/core/browser/language_model.cc
+++ b/components/translate/core/browser/language_model.cc
@@ -132,4 +132,14 @@ void LanguageModel::OnPageVisited(const std::string& language_code) {
     DiscountAndCleanCounters(dict);
 }
 
+void LanguageModel::ClearHistory(base::Time begin, base::Time end) {
+  // Ignore all partial removals and react only to "entire" history removal.

[msramek, 2017/01/24 15:35:34]

This might be worth documenting in the CBDRD unittest. Before you run the
(base::Time(), base::Time::Max()) removal, please add another step where the
time interval is finite and test that the model is unchanged.

[jkrcal, 2017/01/25 08:48:54]

Done.

+  bool is_entire_history = (begin == base::Time() && end == base::Time::Max());
+  if (!is_entire_history) {
+    return;
+  }
+
+  pref_service_->ClearPref(kLanguageModelCounters);
+}
+
 }  // namespace translate