Make flat containers stable, allow constructing from vector.

base/containers/flat_set_unittest.cc

Index: base/containers/flat_set_unittest.cc
diff --git a/base/containers/flat_set_unittest.cc b/base/containers/flat_set_unittest.cc
index 26bb4da4a6110cab781535455682a566a8040cf9..dc024fcf0a9729a15d4987e3980da46306a6b143 100644
--- a/base/containers/flat_set_unittest.cc
+++ b/base/containers/flat_set_unittest.cc
@@ -37,15 +37,16 @@ TEST(FlatSet, IncompleteType) {
 TEST(FlatSet, RangeConstructor) {
   flat_set<int>::value_type input_vals[] = {1, 1, 1, 2, 2, 2, 3, 3, 3};
 
-  flat_set<int> cont(std::begin(input_vals), std::end(input_vals));
+  flat_set<int> cont(std::begin(input_vals), std::end(input_vals),
+                     base::KEEP_FIRST_OF_DUPES);
   EXPECT_THAT(cont, ElementsAre(1, 2, 3));
 }
 
 TEST(FlatSet, MoveConstructor) {
   int input_range[] = {1, 2, 3, 4};
 
-  flat_set<MoveOnlyInt> original(std::begin(input_range),
-                                 std::end(input_range));
+  flat_set<MoveOnlyInt> original(std::begin(input_range), std::end(input_range),
+                                 base::KEEP_FIRST_OF_DUPES);
   flat_set<MoveOnlyInt> moved(std::move(original));
 
   EXPECT_EQ(1U, moved.count(MoveOnlyInt(1)));
@@ -55,7 +56,7 @@ TEST(FlatSet, MoveConstructor) {
 }
 
 TEST(FlatSet, InitializerListConstructor) {
-  flat_set<int> cont{1, 2, 3, 4, 5, 6, 10, 8};
+  flat_set<int> cont({1, 2, 3, 4, 5, 6, 10, 8}, KEEP_FIRST_OF_DUPES);
   EXPECT_THAT(cont, ElementsAre(1, 2, 3, 4, 5, 6, 8, 10));
 }