Replace uses of hash_map in //base

base/id_map_unittest.cc

Index: base/id_map_unittest.cc
diff --git a/base/id_map_unittest.cc b/base/id_map_unittest.cc
index 42949bb5b95c25ba3e91e5fd801693e0fe359ba6..15f0c24b73ad4397ef83d6f88eb9575ae2b57af1 100644
--- a/base/id_map_unittest.cc
+++ b/base/id_map_unittest.cc
@@ -106,7 +106,7 @@ TEST(IDMapTest, IteratorRemainsValidWhenRemovingOtherElements) {
   for (int i = 0; i < kCount; i++)
     map.Add(&obj[i]);
 
-  // IDMap uses a hash_map, which has no predictable iteration order.
+  // IDMap has no predictable iteration order.

[Łukasz Anforowicz, 2017/04/24 18:46:10]

Thanks for making the comment more generic - this is great.

nit: Do you think this comment should also be made part of the public contract
of the IDMap (e.g. by also adding an equivalent of this comment to the doc
comments of IdMap::Iterator class)?

   int32_t ids_in_iteration_order[kCount];
   const TestObject* objs_in_iteration_order[kCount];
   int counter = 0;
@@ -216,7 +216,7 @@ TEST(IDMapTest, IteratorRemainsValidWhenClearing) {
   for (int i = 0; i < kCount; i++)
     map.Add(&obj[i]);
 
-  // IDMap uses a hash_map, which has no predictable iteration order.
+  // IDMap has no predictable iteration order.
   int32_t ids_in_iteration_order[kCount];
   const TestObject* objs_in_iteration_order[kCount];
   int counter = 0;