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

base/chromeos/memory_pressure_observer_chromeos.h

Index: base/chromeos/memory_pressure_observer_chromeos.h
diff --git a/base/chromeos/memory_pressure_observer_chromeos.h b/base/chromeos/memory_pressure_observer_chromeos.h
index 9af07d41d4789fd40a886123e4fdb3ae89cf39f5..b4d2821f55f1bb59a7036d797dea9ab4ec0a668f 100644
--- a/base/chromeos/memory_pressure_observer_chromeos.h
+++ b/base/chromeos/memory_pressure_observer_chromeos.h
@@ -50,6 +50,10 @@ class BASE_EXPORT MemoryPressureObserverChromeOS {
   explicit MemoryPressureObserverChromeOS(MemoryPressureThresholds thresholds);
   virtual ~MemoryPressureObserverChromeOS();
 
+  // Return the memory pressure management threshold. Controlled by a flag and
+  // FieldTrial.

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

Not here.

+  static MemoryPressureThresholds GetMemoryPressureThresholds();
+
   // Redo the memory pressure calculation soon and call again if a critical
   // memory pressure prevails. Note that this call will trigger an asynchronous
   // action which gives the system time to release memory back into the pool.