add experimental param to control the triggering threshold to default Always Translate checked

components/translate/core/browser/translate_ui_delegate_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/translate/core/browser/translate_ui_delegate.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
 #include "components/infobars/core/infobar.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/pref_registry/testing_pref_service_syncable.h"
 #include "components/translate/core/browser/mock_translate_driver.h"
 #include "components/translate/core/browser/translate_client.h"
 #include "components/translate/core/browser/translate_infobar_delegate.h"
 #include "components/translate/core/browser/translate_manager.h"
 #include "components/translate/core/browser/translate_prefs.h"
+#include "components/variations/variations_associated_data.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
 using testing::Return;
 using testing::Test;
 using translate::testing::MockTranslateDriver;
 
 namespace translate {
 
@@ skipping 157 matching lines @@
   // Reset it to true again after delegate_->SetLanguageBlocked(true)
   // turn it to false.
   manager_->GetLanguageState().SetTranslateEnabled(true);
 
   delegate_->SetLanguageBlocked(false);
 
   EXPECT_FALSE(prefs->IsBlockedLanguage("ar"));
   EXPECT_TRUE(manager_->GetLanguageState().translate_enabled());
 }
 
-TEST_F(TranslateUIDelegateTest, ShouldAlwaysTranslateBeCheckedByDefault) {
+TEST_F(TranslateUIDelegateTest, ShouldAlwaysTranslateBeCheckedByDefaultNever) {
   std::unique_ptr<TranslatePrefs> prefs(client_->GetTranslatePrefs());
   prefs->ResetTranslationAcceptedCount("ar");
 
+  for (int i = 0; i < 100; i++) {
+    EXPECT_FALSE(delegate_->ShouldAlwaysTranslateBeCheckedByDefault());
+    prefs->IncrementTranslationAcceptedCount("ar");
+  }
+}
+
+TEST_F(TranslateUIDelegateTest, ShouldAlwaysTranslateBeCheckedByDefault2) {
+  const char kGroupName[] = "GroupA";
+  std::map<std::string, std::string> params = {
+      {kAlwaysTranslateOfferThreshold, "2"}};
+  variations::AssociateVariationParams(translate::kTranslateUI2016Q2TrialName,
+                                       kGroupName, params);
+  // need a trial_list to init the global instance used internally
+  // inside CreateFieldTrial().
+  base::FieldTrialList trial_list(nullptr);
+  base::FieldTrialList::CreateFieldTrial(translate::kTranslateUI2016Q2TrialName,
+                                         kGroupName);
+
+  std::unique_ptr<TranslatePrefs> prefs(client_->GetTranslatePrefs());
+  prefs->ResetTranslationAcceptedCount("ar");
+
   for (int i = 0; i < 2; i++) {
     EXPECT_FALSE(delegate_->ShouldAlwaysTranslateBeCheckedByDefault());
     prefs->IncrementTranslationAcceptedCount("ar");
   }
   EXPECT_TRUE(delegate_->ShouldAlwaysTranslateBeCheckedByDefault());
   prefs->IncrementTranslationAcceptedCount("ar");
 
   EXPECT_FALSE(delegate_->ShouldAlwaysTranslateBeCheckedByDefault());
 }
 
 // TODO(ftang) Currently this file only test TranslationDeclined(), we
 // need to add the test for other functions soon to increase the test
 // coverage.
 
 }  // namespace translate