Add a finch experiment for different memory pressure management strategies in ChromeOS.

base/chromeos/memory_pressure_observer_chromeos.cc

 // Copyright 2014 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 "base/chromeos/memory_pressure_observer_chromeos.h"
 
+#include "chromeos/chromeos_switches.h"
+#include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/process/process_metrics.h"
 #include "base/time/time.h"
 
 namespace base {
 
 namespace {
 
 // The time between memory pressure checks. While under critical pressure, this
 // is also the timer to repeat cleanup attempts.
@@ skipping 183 matching lines @@
 
   // Available memory is the sum of free, swap and easy reclaimable memory.
   int available_memory =
       info.free + info.swap_free / kSwapWeight + file_memory;
 
   DCHECK(available_memory < total_memory);
   int percentage = ((total_memory - available_memory) * 100) / total_memory;
   return percentage;
 }
 
+// static function
+MemoryPressureObserverChromeOS::MemoryPressureThresholds
+MemoryPressureObserverChromeOS::GetMemoryPressureThresholds() {

[Mr4D (OOO till 08-26), 2015/02/06 03:56:35]

This should remain in chromeos_switches.cc. Having this in base is not an
option.

+  const std::string option =
+      base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          chromeos::switches::kMemoryPressureThresholds);
+  if (option == chromeos::switches::kConservativeThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_CONSERVATIVE;
+  if (option == chromeos::switches::kAggressiveCacheDiscardThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE_CACHE_DISCARD;
+  if (option == chromeos::switches::kAggressiveTabDiscardThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE_TAB_DISCARD;
+  if (option == chromeos::switches::kAggressiveThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE;
+
+  const std::string group_name = base::FieldTrialList::FindFullName(
+      chromeos::switches::kMemoryPressureThresholds);
+  if (group_name == chromeos::switches::kConservativeThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_CONSERVATIVE;
+  if (group_name == chromeos::switches::kAggressiveCacheDiscardThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE_CACHE_DISCARD;
+  if (group_name == chromeos::switches::kAggressiveTabDiscardThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE_TAB_DISCARD;
+  if (group_name == chromeos::switches::kAggressiveThreshold)
+    return MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE;
+
+  return MemoryPressureObserverChromeOS::THRESHOLD_DEFAULT;
+}
+
 }  // namespace base