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

components/arc/metrics/arc_metrics_service.cc

 // 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.
 
 #include "components/arc/metrics/arc_metrics_service.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_util.h"
 
 namespace {
 
 const int kRequestProcessListPeriodInMinutes = 5;
 const char kArcProcessNamePrefix[] = "org.chromium.arc.";
 const char kGmsProcessNamePrefix[] = "com.google.android.gms";
 
 } // namespace
 
 namespace arc {
 
 ArcMetricsService::ArcMetricsService(ArcBridgeService* bridge_service)
     : ArcService(bridge_service), weak_ptr_factory_(this) {
   arc_bridge_service()->AddObserver(this);
+  low_memory_killer_minotor_.Start();
 }
 
 ArcMetricsService::~ArcMetricsService() {
   DCHECK(CalledOnValidThread());
   arc_bridge_service()->RemoveObserver(this);
 }
 
 bool ArcMetricsService::CalledOnValidThread() {
   // Make sure access to the Chrome clipboard is happening in the UI thread.
   return thread_checker_.CalledOnValidThread();
@@ skipping 47 matching lines @@
       VLOG(2) << "Skipped " << process_name << " " << process_state;
     } else {
       ++running_app_count;
     }
   }
 
   UMA_HISTOGRAM_COUNTS_100("Arc.AppCount", running_app_count);
 }
 
 }  // namespace arc