Move and rename TaskTimeTracker to public interface exposed to WebThread, use in WebPerf Agent.

third_party/WebKit/Source/platform/scheduler/base/task_queue_manager_perftest.cc

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_manager_perftest.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager_perftest.cc b/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager_perftest.cc
index 4a2bb43b94a78fdea37a5f457e80a549cd6cca3d..865f62fc60abf0cd13986d6d07a8f34764c8e780 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager_perftest.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager_perftest.cc
@@ -14,7 +14,7 @@
 #include "platform/scheduler/base/task_queue_impl.h"
 #include "platform/scheduler/base/task_queue_manager_delegate_for_test.h"
 #include "platform/scheduler/base/task_queue_selector.h"
-#include "platform/scheduler/base/test_task_time_tracker.h"
+#include "platform/scheduler/base/test_task_time_observer.h"
 #include "platform/scheduler/base/work_queue_sets.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/perf/perf_test.h"
@@ -45,7 +45,7 @@ class TaskQueueManagerPerfTest : public testing::Test {
             message_loop_->task_runner(),
             base::WrapUnique(new base::DefaultTickClock())),
         "fake.category", "fake.category", "fake.category.debug");
-    manager_->SetTaskTimeTracker(&test_task_time_tracker_);
+    manager_->SetTaskTimeObserver(&test_task_time_observer_);
     for (size_t i = 0; i < num_queues; i++)
       queues_.push_back(manager_->NewTaskQueue(TaskQueue::Spec("test")));
   }
@@ -118,8 +118,8 @@ class TaskQueueManagerPerfTest : public testing::Test {
   std::unique_ptr<base::RunLoop> run_loop_;
   std::vector<scoped_refptr<base::SingleThreadTaskRunner>> queues_;
   // TODO(alexclarke): parameterize so we can measure with and without a
-  // TaskTimeTracker.
-  TestTaskTimeTracker test_task_time_tracker_;
+  // TaskTimeObserver.
+  TestTaskTimeObserver test_task_time_observer_;
 };
 
 TEST_F(TaskQueueManagerPerfTest, RunTenThousandDelayedTasks_OneQueue) {