Record task durations on Renderer Main & Compositor threads.

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

Index: third_party/WebKit/Source/platform/scheduler/child/webthread_base.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/child/webthread_base.cc b/third_party/WebKit/Source/platform/scheduler/child/webthread_base.cc
index 888ecc8eef2d170c305a22bcd2fca66eb014bdeb..dc3e0c7daeb5b8f72b2b4183915e6f2056674c3e 100644
--- a/third_party/WebKit/Source/platform/scheduler/child/webthread_base.cc
+++ b/third_party/WebKit/Source/platform/scheduler/child/webthread_base.cc
@@ -13,6 +13,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/pending_task.h"
 #include "base/threading/platform_thread.h"
+#include "base/tracked_objects.h"
 #include "platform/scheduler/child/compositor_worker_scheduler.h"
 #include "platform/scheduler/child/scheduler_tqm_delegate_impl.h"
 #include "platform/scheduler/child/webthread_impl_for_worker_scheduler.h"
@@ -119,6 +120,7 @@ class WebThreadForCompositor : public WebThreadImplForWorkerScheduler {
   // WebThreadImplForWorkerScheduler:
   std::unique_ptr<blink::scheduler::WorkerScheduler> CreateWorkerScheduler()
       override {
+    tracked_objects::ThreadData::Get()->EnableTaskDurationRecordingForUMA();
     return base::MakeUnique<CompositorWorkerScheduler>(GetThread(),
                                                        task_runner_delegate());
   }