[Extensions] Fix FeatureProvider::GetChildren()

extensions/common/features/feature_provider_unittest.cc

 // Copyright 2014 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 "extensions/common/features/feature_provider.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <utility>
 
+#include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
 #include "extensions/common/extension_builder.h"
 #include "extensions/common/features/feature.h"
 #include "extensions/common/features/simple_feature.h"
 #include "extensions/common/manifest.h"
 #include "extensions/common/value_builder.h"
+#include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace extensions {
 
 // Tests that a real manifest feature is available for the correct types of
 // extensions and apps.
 TEST(FeatureProviderTest, ManifestFeatureTypes) {
   // NOTE: This feature cannot have multiple rules, otherwise it is not a
   // SimpleFeature.
   const SimpleFeature* feature = static_cast<const SimpleFeature*>(
@@ skipping 115 matching lines @@
   // A permission that isn't part of the manifest returns NOT_PRESENT.
   feature = provider->GetFeature("serial");
   ASSERT_TRUE(feature);
   EXPECT_EQ(Feature::NOT_PRESENT,
             feature
                 ->IsAvailableToContext(app.get(), Feature::UNSPECIFIED_CONTEXT,
                                        GURL())
                 .result());
 }
 
+TEST(FeatureProviderTest, GetChildren) {
+  FeatureProvider provider;
+
+  auto add_feature = [&provider](base::StringPiece name,
+                                 bool no_parent = false) {
+    auto feature = base::MakeUnique<SimpleFeature>();
+    feature->set_name(name);
+    feature->set_noparent(no_parent);
+    provider.AddFeature(name, std::move(feature));
+  };
+
+  add_feature("parent");
+  add_feature("parent.child");
+  add_feature("parent.child.grandchild");
+  add_feature("parent.other_child.other_grandchild");
+  add_feature("parent.unparented_child", true);
+
+  Feature* parent = provider.GetFeature("parent");
+  ASSERT_TRUE(parent);
+  std::vector<Feature*> children = provider.GetChildren(*parent);
+  std::set<std::string> children_names;
+  for (const Feature* child : children)
+    children_names.insert(child->name());
+  EXPECT_THAT(children_names, testing::UnorderedElementsAre(
+                                  "parent.child", "parent.child.grandchild",
+                                  "parent.other_child.other_grandchild"));
+}
+
 }  // namespace extensions