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

base/stl_util.h

Index: base/stl_util.h
diff --git a/base/stl_util.h b/base/stl_util.h
index 12e226a9db9b106b95f9500efe684463d1ecd1f2..352344eeff94b046a26f54e6a5ec72343e10d59b 100644
--- a/base/stl_util.h
+++ b/base/stl_util.h
@@ -257,6 +257,16 @@ bool STLIncludes(const Arg1& a1, const Arg2& a2) {
                        a2.begin(), a2.end());
 }
 
+// Moves out and removes the top element of a std::priority_queue.
+template <typename PriorityQueue>

[Nico, 2016/04/22 15:32:16]

this is only called from two places. the loop is in at least three. not sure if
it makes sense to put this here but don't put the other thing here

[tzik, 2016/04/25 11:36:26]

Hmm, there are several user of the pattern. And I think this is a hacky code
that should not be distributed throughout Chromium.
Anyway, let me inline this function to the caller now, and propose it
separately.

+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_