Introduce a FlatMap and FlatSet into WTF

third_party/WebKit/Source/platform/scheduler/base/work_queue_sets_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 "platform/scheduler/base/work_queue_sets.h"
 
 #include <stddef.h>
 
 #include "base/memory/ptr_util.h"
 #include "platform/scheduler/base/work_queue.h"
@@ skipping 61 matching lines @@
 
 TEST_F(WorkQueueSetsTest, OnPushQueue) {
   WorkQueue* work_queue = NewTaskQueue("queue");
   size_t set = TaskQueue::NORMAL_PRIORITY;
   work_queue_sets_->ChangeSetIndex(work_queue, set);
 
   WorkQueue* selected_work_queue;
   EXPECT_FALSE(
       work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
 
+  // Calls OnPushQueue.
   work_queue->Push(FakeTaskWithEnqueueOrder(10));
-  work_queue_sets_->OnPushQueue(work_queue);
 
   EXPECT_TRUE(work_queue_sets_->GetOldestQueueInSet(set, &selected_work_queue));
   EXPECT_EQ(work_queue, selected_work_queue);
 }
 
 TEST_F(WorkQueueSetsTest, GetOldestQueueInSet_SingleTaskInSet) {
   WorkQueue* work_queue = NewTaskQueue("queue");
   work_queue->Push(FakeTaskWithEnqueueOrder(10));
   size_t set = 1;
   work_queue_sets_->ChangeSetIndex(work_queue, set);
@@ skipping 158 matching lines @@
   EXPECT_FALSE(work_queue_sets_->IsSetEmpty(set));
 
   work_queue->PopTaskForTest();
   work_queue_sets_->OnPopQueue(work_queue);
   EXPECT_TRUE(work_queue_sets_->IsSetEmpty(set));
 }
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink