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

base/chromeos/memory_pressure_observer_chromeos.cc

Index: base/chromeos/memory_pressure_observer_chromeos.cc
diff --git a/base/chromeos/memory_pressure_observer_chromeos.cc b/base/chromeos/memory_pressure_observer_chromeos.cc
index 5691eb8b4ed1dbd626e85ef1ea617886396eeafd..641aa40d2d5ec704fd087b59c2f3b06545f1ed75 100644
--- a/base/chromeos/memory_pressure_observer_chromeos.cc
+++ b/base/chromeos/memory_pressure_observer_chromeos.cc
@@ -4,7 +4,10 @@
 
 #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"
@@ -208,4 +211,33 @@ int MemoryPressureObserverChromeOS::GetUsedMemoryInPercent() {
   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