Introduce UserHiveVisitor for performing operations on local users' registry hives.

chrome/installer/setup/user_hive_visitor_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 "chrome/installer/setup/user_hive_visitor.h"
+
+#include <vector>
+
+#include "base/bind.h"
+#include "base/macros.h"
+#include "base/strings/string16.h"
+#include "base/win/registry.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace installer {
+
+namespace {
+
+class UserHiveVisitor {
+ public:
+  UserHiveVisitor() = default;
+
+  bool OnUserHive(const wchar_t* sid, base::win::RegKey* key) {
+    EXPECT_NE(nullptr, sid);
+    EXPECT_STRNE(L"", sid);
+    EXPECT_NE(nullptr, key);
+    EXPECT_TRUE(key->Valid());
+    sids_visited_.push_back(sid);
+    return !early_exit_;
+  }
+
+  void set_early_exit(bool early_exit) { early_exit_ = early_exit; }
+
+  const std::vector<base::string16> sids_visited() const {
+    return sids_visited_;
+  }
+
+ private:
+  std::vector<base::string16> sids_visited_;
+  bool early_exit_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(UserHiveVisitor);
+};
+
+}  // namespace
+
+// Tests that the visitor visits at least one user hive. This will succeed even
+// when run as an ordinary user, as the current user's hive is always available.
+TEST(UserHiveVisitorTest, VisitAllUserHives) {
+  UserHiveVisitor visitor;
+
+  VisitUserHives(
+      base::Bind(&UserHiveVisitor::OnUserHive, base::Unretained(&visitor)));
+
+  EXPECT_GT(visitor.sids_visited().size(), 0U);
+}
+
+// Tests that only one user hive is visited when the visitor returns false to
+// stop the iteration.
+TEST(UserHiveVisitor, VisitOneHive) {
+  UserHiveVisitor visitor;
+
+  visitor.set_early_exit(true);
+  VisitUserHives(
+      base::Bind(&UserHiveVisitor::OnUserHive, base::Unretained(&visitor)));
+
+  EXPECT_EQ(1U, visitor.sids_visited().size());
+}
+
+}  // namespace installer