Make PendingTask move-only and pass it by value on retaining params

base/stl_util.h

 // Copyright (c) 2011 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.
 
 // Derived from google3/util/gtl/stl_util.h
 
 #ifndef BASE_STL_UTIL_H_
 #define BASE_STL_UTIL_H_
 
 #include <algorithm>
@@ skipping 239 matching lines @@
 // Returns true if the sorted container |a1| contains all elements of the sorted
 // container |a2|.
 template <typename Arg1, typename Arg2>
 bool STLIncludes(const Arg1& a1, const Arg2& a2) {
   DCHECK(STLIsSorted(a1));
   DCHECK(STLIsSorted(a2));
   return std::includes(a1.begin(), a1.end(),
                        a2.begin(), a2.end());
 }
 
+template <typename PriorityQueue>
+typename PriorityQueue::value_type
+PopOutFromPriorityQueue(PriorityQueue* queue) {
+  using ValueType = typename PriorityQueue::value_type;
+  ValueType ret = std::move(const_cast<ValueType&>(queue->top()));
+  queue->pop();
+  return ret;
+}
+
 }  // namespace base
 
 #endif  // BASE_STL_UTIL_H_