Revert of Move JoinString to the base namespace

components/view_manager/gesture_manager_unittest.cc

 // Copyright 2015 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/view_manager/gesture_manager.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "components/view_manager/gesture_manager_delegate.h"
 #include "components/view_manager/public/cpp/keys.h"
@@ skipping 90 matching lines @@
 }
 
 }  // namespace
 
 class TestGestureManagerDelegate : public GestureManagerDelegate {
  public:
   TestGestureManagerDelegate() {}
   ~TestGestureManagerDelegate() override {}
 
   std::string GetAndClearDescriptions() {
-    const std::string result(base::JoinString(descriptions_, "\n"));
+    const std::string result(JoinString(descriptions_, '\n'));
     descriptions_.clear();
     return result;
   }
 
   std::vector<std::string>& descriptions() { return descriptions_; }
 
   void AppendDescriptionsFromResults(const ChangeMap& change_map) {
     std::set<const ServerView*, CompareViewByConnectionId> views_by_id;
     for (const auto& pair : change_map)
       views_by_id.insert(pair.first);
@@ skipping 337 matching lines @@
   EXPECT_EQ(std::string(), gesture_delegate_.GetAndClearDescriptions());
 
   // Respond from the first view, with no gesture, should unblock cancel.
   SetGestures(&root_, pointer_id, kInvalidGestureId, SetWith(5u, 10u),
               std::set<uint32_t>());
   EXPECT_EQ("cancel pointer=1 connection=1 chosen=false",
             gesture_delegate_.GetAndClearDescriptions());
 }
 
 }  // namespace view_manager