Fix WorkerThread.Runtime UMA

third_party/WebKit/Source/platform/scheduler/child/worker_scheduler_impl.cc

 // Copyright 2014 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/child/worker_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ skipping 63 matching lines @@
 
 void WorkerSchedulerImpl::RemoveTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   DCHECK(initialized_);
   helper_.RemoveTaskObserver(task_observer);
 }
 
 void WorkerSchedulerImpl::Shutdown() {
   DCHECK(initialized_);
   base::TimeTicks end_time = helper_.scheduler_tqm_delegate()->NowTicks();
-  base::TimeDelta delta = thread_start_time_ - end_time;
+  base::TimeDelta delta = end_time - thread_start_time_;
 
   // The lifetime could be radically different for different workers,
   // some workers could be short-lived (but last at least 1 sec in
   // Service Workers case) or could be around as long as the tab is open.
   UMA_HISTOGRAM_CUSTOM_TIMES(
       "WorkerThread.Runtime", delta, base::TimeDelta::FromSeconds(1),
       base::TimeDelta::FromDays(1), 50 /* bucket count */);
   helper_.Shutdown();
 }
 
 SchedulerHelper* WorkerSchedulerImpl::GetSchedulerHelperForTesting() {
   return &helper_;
 }
 
 bool WorkerSchedulerImpl::CanEnterLongIdlePeriod(base::TimeTicks,
                                                  base::TimeDelta*) {
   return true;
 }
 
 base::TimeTicks WorkerSchedulerImpl::CurrentIdleTaskDeadlineForTesting() const {
   return idle_helper_.CurrentIdleTaskDeadline();
 }
 
 }  // namespace scheduler
 }  // namespace blink