Enable UMA histogram logger for low memor kill events in ArcMetricsService.

components/arc/metrics/arc_metrics_service.h

 // Copyright 2016 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.
 
 #ifndef COMPONENTS_ARC_METRICS_ARC_METRICS_SERVICE_H
 #define COMPONENTS_ARC_METRICS_ARC_METRICS_SERVICE_H
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/timer/timer.h"
 #include "components/arc/arc_bridge_service.h"
 #include "components/arc/arc_service.h"
 #include "components/arc/common/arc_bridge.mojom.h"
+#include "components/arc/metrics/arc_low_memory_killer_monitor.h"
 
 namespace arc {
 
 // Collects information from other ArcServices and send UMA metrics.
 class ArcMetricsService : public ArcService,
                           public ArcBridgeService::Observer {
  public:
   explicit ArcMetricsService(ArcBridgeService* bridge_service);
   ~ArcMetricsService() override;
 
   // ArcBridgeService::Observer overrides.
   void OnProcessInstanceReady() override;
   void OnProcessInstanceClosed() override;
 
  private:
   bool CalledOnValidThread();
   void RequestProcessList();
   void ParseProcessList(mojo::Array<arc::RunningAppProcessInfoPtr> processes);
 
   base::ThreadChecker thread_checker_;
   base::RepeatingTimer timer_;
 
+  ArcLowMemoryKillerMonitor low_memory_killer_minotor_;
+
   // Always keep this the last member of this class to make sure it's the
   // first thing to be destructed.
   base::WeakPtrFactory<ArcMetricsService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcMetricsService);
 };
 
 }  // namespace arc
 
-#endif  // COMPONENTS_ARC_METRICS_ARC_METRICS_SERVICE_H
+#endif  // COMPONENTS_ARC_METRICS_ARC_METRICS_SERVICE_H