WIP: memory coordinator: Check /dev/chromeos-low-mem to determine memory condition

content/browser/memory/memory_condition_observer.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 "content/browser/memory/memory_condition_observer.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/browser/memory/memory_monitor.h"
@@ skipping 46 matching lines @@
     *target = base::TimeDelta::FromSeconds(value);
   }
 }
 
 }  // namespace
 
 MemoryConditionObserver::MemoryConditionObserver(
     MemoryCoordinatorImpl* coordinator,
     scoped_refptr<base::SingleThreadTaskRunner> task_runner)
     : coordinator_(coordinator), task_runner_(task_runner) {
+#if defined(OS_CHROMEOS)
+  low_memory_observer_ = base::MakeUnique<base::chromeos::LowMemoryObserver>();
+#endif
   DCHECK(coordinator_);
   InitializeParameters();
   DCHECK(ValidateParameters());
 }
 
 MemoryConditionObserver::~MemoryConditionObserver() {}
 
 void MemoryConditionObserver::ScheduleUpdateCondition(base::TimeDelta delay) {
   update_condition_closure_.Reset(base::Bind(
       &MemoryConditionObserver::UpdateCondition, base::Unretained(this)));
@@ skipping 11 matching lines @@
 
 void MemoryConditionObserver::SetMonitoringInterval(base::TimeDelta interval) {
   DCHECK(!interval.is_zero());
   if (interval == monitoring_interval_)
     return;
   monitoring_interval_ = interval;
   ScheduleUpdateCondition(interval);
 }
 
 MemoryCondition MemoryConditionObserver::CalculateNextCondition() {
+#if defined(OS_CHROMEOS)
+  if (low_memory_observer_->IsLowMemoryCondition())
+    return MemoryCondition::CRITICAL;
+#endif
+
   int available =
       coordinator_->memory_monitor()->GetFreeMemoryUntilCriticalMB();
 
   // TODO(chrisha): Move this histogram recording to a better place when
   // https://codereview.chromium.org/2479673002/ is landed.
   UMA_HISTOGRAM_MEMORY_LARGE_MB("Memory.Coordinator.FreeMemoryUntilCritical",
                                 available);
 
   if (available <= 0)
     return MemoryCondition::CRITICAL;
@@ skipping 67 matching lines @@
 }
 
 bool MemoryConditionObserver::ValidateParameters() {
   return (new_renderers_until_warning_ > new_renderers_until_critical_) &&
          (new_renderers_back_to_normal_ > new_renderers_back_to_warning_) &&
          (new_renderers_back_to_normal_ > new_renderers_until_warning_) &&
          (new_renderers_back_to_warning_ > new_renderers_until_critical_);
 }
 
 }  // namespace content