cros: Remove some OS platform ifdefs from ash

ash/metrics/user_metrics_recorder.cc

Index: ash/metrics/user_metrics_recorder.cc
diff --git a/ash/metrics/user_metrics_recorder.cc b/ash/metrics/user_metrics_recorder.cc
index 30608bacbea9e08ff9f25238721fe8d78c635c6b..468973e8bfa0275e560006cce6a197921f2f31da 100644
--- a/ash/metrics/user_metrics_recorder.cc
+++ b/ash/metrics/user_metrics_recorder.cc
@@ -4,6 +4,7 @@
 
 #include "ash/metrics/user_metrics_recorder.h"
 
+#include "ash/common/metrics/pointer_metrics_recorder.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shelf/shelf_delegate.h"
 #include "ash/common/shelf/shelf_item_types.h"
@@ -23,10 +24,6 @@
 #include "base/metrics/user_metrics.h"
 #include "ui/aura/window.h"
 
-#if defined(OS_CHROMEOS)
-#include "ash/common/metrics/pointer_metrics_recorder.h"
-#endif
-
 namespace ash {
 
 namespace {
@@ -604,20 +601,16 @@ void UserMetricsRecorder::OnShellInitialized() {
     desktop_task_switch_metric_recorder_.reset(
         new DesktopTaskSwitchMetricRecorder());
   }
-#if defined(OS_CHROMEOS)
   pointer_metrics_recorder_ = base::MakeUnique<PointerMetricsRecorder>();
-#endif
 }
 
 void UserMetricsRecorder::OnShellShuttingDown() {
   desktop_task_switch_metric_recorder_.reset();
 
-#if defined(OS_CHROMEOS)
   // To clean up pointer_metrics_recorder_ properly, a valid shell instance is
   // required, so explicitly delete it before the shell instance becomes
   // invalid.
   pointer_metrics_recorder_.reset();
-#endif
 }
 
 void UserMetricsRecorder::RecordPeriodicMetrics() {