memory coordinator: Purge memory under memory pressure

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 10 matching lines @@
 const int kDefaultExpectedRendererSizeMB = 70;
 #else  // Mac, Linux, and ChromeOS
 const int kDefaultExpectedRendererSizeMB = 120;
 #endif
 
 // Default values for parameters to determine the global state.
 const int kDefaultNewRenderersUntilWarning = 4;
 const int kDefaultNewRenderersUntilCritical = 2;
 const int kDefaultNewRenderersBackToNormal = 5;
 const int kDefaultNewRenderersBackToWarning = 3;
-const int kDefaultMonitoringIntervalSeconds = 5;
+const int kDefaultMonitoringIntervalSeconds = 1;

[bashi, 2017/03/28 05:48:36]

It seems that base::chromeos::MemoryPressureMonitor uses 1 sec for the interval.
I think we should use the same interval.

 const int kMonitoringIntervalBackgroundedSeconds = 120;
 
 void SetIntVariationParameter(const std::map<std::string, std::string> params,
                               const char* name,
                               int* target) {
   const auto& iter = params.find(name);
   if (iter == params.end())
     return;
   int value;
   if (!iter->second.empty() && base::StringToInt(iter->second, &value)) {
@@ skipping 133 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