Report expected task queueing time via UMA

components/scheduler/base/task_queue_manager_perftest.cc

Index: components/scheduler/base/task_queue_manager_perftest.cc
diff --git a/components/scheduler/base/task_queue_manager_perftest.cc b/components/scheduler/base/task_queue_manager_perftest.cc
index a81fea329dc4cdb7dff034c92c5dbd5a6bb15787..377133552e8fbe2359adb01192e7fe0a7983b61a 100644
--- a/components/scheduler/base/task_queue_manager_perftest.cc
+++ b/components/scheduler/base/task_queue_manager_perftest.cc
@@ -13,6 +13,7 @@
 #include "components/scheduler/base/task_queue_impl.h"
 #include "components/scheduler/base/task_queue_manager_delegate_for_test.h"
 #include "components/scheduler/base/task_queue_selector.h"
+#include "components/scheduler/base/task_time_tracker.h"
 #include "components/scheduler/base/work_queue_sets.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/perf/perf_test.h"
@@ -26,7 +27,8 @@ class TaskQueueManagerPerfTest : public testing::Test {
         max_tasks_in_flight_(0),
         num_tasks_in_flight_(0),
         num_tasks_to_post_(0),
-        num_tasks_to_run_(0) {}
+        num_tasks_to_run_(0),
+        task_time_tracker_(nullptr) {}
 
   void SetUp() override {
     if (base::ThreadTicks::IsSupported())
@@ -41,6 +43,7 @@ class TaskQueueManagerPerfTest : public testing::Test {
             message_loop_->task_runner(),
             base::WrapUnique(new base::DefaultTickClock())),
         "fake.category", "fake.category", "fake.category.debug"));
+    manager_->SetTaskTimeTracker(&task_time_tracker_);
     for (size_t i = 0; i < num_queues; i++)
       queues_.push_back(manager_->NewTaskQueue(TaskQueue::Spec("test")));
   }
@@ -111,6 +114,7 @@ class TaskQueueManagerPerfTest : public testing::Test {
   std::unique_ptr<TaskQueueManager> manager_;
   std::unique_ptr<base::MessageLoop> message_loop_;
   std::vector<scoped_refptr<base::SingleThreadTaskRunner>> queues_;
+  TaskTimeTracker task_time_tracker_;

[alex clarke (OOO till 29th), 2016/07/06 09:51:39]

Can you add a TODO(alexclarke): parameterize so we can measure with and without
this

[tdresser, 2016/07/06 13:25:34]

Done.

 };
 
 TEST_F(TaskQueueManagerPerfTest, RunTenThousandDelayedTasks_OneQueue) {