Convert the overlay scrollbar flag to use FeatureList

base/test/scoped_feature_list_unittest.cc

Index: base/test/scoped_feature_list_unittest.cc
diff --git a/base/test/scoped_feature_list_unittest.cc b/base/test/scoped_feature_list_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bd32d1a34ee87205042fdb1224945896d939a9d0
--- /dev/null
+++ b/base/test/scoped_feature_list_unittest.cc
@@ -0,0 +1,80 @@
+// Copyright 2017 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 "base/test/scoped_feature_list.h"
+
+#include <string>
+
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+class ScopedFeatureListTest : public testing::Test {
+ public:
+  void SetUp() override {
+    // Clear default feature list;
+    feature_list.Init();
+  }
+
+  void ExpectFeatures(const std::string& enabled_features,
+                      const std::string& disabled_features) {
+    base::FeatureList* list = base::FeatureList::GetInstance();
+    std::string actual_enabled_features;
+    std::string actual_disabled_features;
+
+    list->GetFeatureOverrides(&actual_enabled_features,
+                              &actual_disabled_features);
+
+    EXPECT_EQ(enabled_features, actual_enabled_features);
+    EXPECT_EQ(disabled_features, actual_disabled_features);
+  }
+
+ private:
+  test::ScopedFeatureList feature_list;
+};
+
+TEST_F(ScopedFeatureListTest, BasicScoped) {
+  ExpectFeatures(std::string(), std::string());
+  {
+    test::ScopedFeatureList feature_list1;
+    feature_list1.InitFromCommandLine(std::string(), "OverlayScrollbar");
+    ExpectFeatures(std::string(), "OverlayScrollbar");
+  }
+  ExpectFeatures(std::string(), std::string());
+}
+
+TEST_F(ScopedFeatureListTest, TestInitWithFeatureListAndOverrides) {
+  ExpectFeatures(std::string(), std::string());
+  {
+    test::ScopedFeatureList feature_list1;
+    std::vector<std::string> features{"OverlayScrollbar"};
+    feature_list1.InitWithFeatureListAndOverrides(
+        nullptr, std::vector<std::string>(), features);
+    ExpectFeatures(std::string(), "OverlayScrollbar");
+
+    {
+      test::ScopedFeatureList feature_list2;
+      ExpectFeatures(std::string(), "OverlayScrollbar");
+      // Given enabled list should override given feature list.
+      feature_list2.InitWithFeatureListAndOverrides(
+          base::FeatureList::GetInstance(), features,
+          std::vector<std::string>());
+      ExpectFeatures("OverlayScrollbar", std::string());
+    }
+
+    {
+      test::ScopedFeatureList feature_list2;
+      ExpectFeatures(std::string(), "OverlayScrollbar");
+      // Given same feature should not appear duplicate in feature list.
+      feature_list2.InitWithFeatureListAndOverrides(
+          base::FeatureList::GetInstance(), std::vector<std::string>(),
+          features);
+      ExpectFeatures(std::string(), "OverlayScrollbar");
+    }
+  }
+  ExpectFeatures(std::string(), std::string());
+}
+
+}  // namespace base