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

chromeos/chromeos_switches.cc

Index: chromeos/chromeos_switches.cc
diff --git a/chromeos/chromeos_switches.cc b/chromeos/chromeos_switches.cc
index f2f5f038f1c5f4ff0570880af49ac465d16724be..34addec71bae068a056e306b23faf36a21ec4a2e 100644
--- a/chromeos/chromeos_switches.cc
+++ b/chromeos/chromeos_switches.cc
@@ -5,6 +5,7 @@
 #include "chromeos/chromeos_switches.h"
 
 #include "base/command_line.h"
+#include "base/metrics/field_trial.h"
 
 // TODO(rsorokin): alphabetize all of these switches so they
 // match the order from the .h file
@@ -221,9 +222,14 @@ const char kLoginProfile[] = "login-profile";
 // Specifies the user which is already logged in.
 const char kLoginUser[] = "login-user";
 
-// The memory pressure thresholds selection which is used to decide when a
-// memory pressure event needs to get fired.
+// The memory pressure thresholds selection which is used to decide whether and
+// when a memory pressure event needs to get fired.
+const char kMemoryPressureHandlingOff[] = "memory-pressure-off";
 const char kMemoryPressureThresholds[] = "memory-pressure-thresholds";
+const char kConservativeThreshold[] = "conservative";
+const char kAggressiveCacheDiscardThreshold[] = "aggressive-cache-discard";
+const char kAggressiveTabDiscardThreshold[] = "aggressive-tab-discard";
+const char kAggressiveThreshold[] = "aggressive";
 
 // Enables natural scroll by default.
 const char kNaturalScrollDefault[] = "enable-natural-scroll-default";
@@ -312,27 +318,45 @@ bool WakeOnWifiEnabled() {
   return !base::CommandLine::ForCurrentProcess()->HasSwitch(kDisableWakeOnWifi);
 }
 
+bool MemoryPressureHandlingEnabled() {
+  if ((base::CommandLine::ForCurrentProcess()->HasSwitch(
+          chromeos::switches::kDisableMemoryPressureSystemChromeOS)) ||
+      (base::FieldTrialList::FindFullName(kMemoryPressureThresholds) ==
+       kMemoryPressureHandlingOff))
+    return false;
+  return true;
+}
+
 base::MemoryPressureObserverChromeOS::MemoryPressureThresholds
 GetMemoryPressureThresholds() {
-  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(

[Mr4D (OOO till 08-26), 2015/02/09 22:16:22]

As stated earlier - this code should remain and you should move the field trial
cases into this if case (since there is no user setting in this case the field
trials can be used).

-          kMemoryPressureThresholds)) {
-    return base::MemoryPressureObserverChromeOS::THRESHOLD_DEFAULT;
-  }
   const std::string option =
       base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
           kMemoryPressureThresholds);
-  if (option == "1") {
+  if (option == kConservativeThreshold)
     return base::MemoryPressureObserverChromeOS::THRESHOLD_CONSERVATIVE;
-  }
-  if (option == "2") {
+  if (option == kAggressiveCacheDiscardThreshold)
     return base::MemoryPressureObserverChromeOS::
         THRESHOLD_AGGRESSIVE_CACHE_DISCARD;
-  }
-  if (option == "3") {
+  if (option == kAggressiveTabDiscardThreshold)
     return base::MemoryPressureObserverChromeOS::
         THRESHOLD_AGGRESSIVE_TAB_DISCARD;
-  }
-  return base::MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE;
+  if (option == kAggressiveThreshold)
+    return base::MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE;
+
+  const std::string group_name =
+      base::FieldTrialList::FindFullName(kMemoryPressureThresholds);
+  if (group_name == kConservativeThreshold)
+    return base::MemoryPressureObserverChromeOS::THRESHOLD_CONSERVATIVE;
+  if (group_name == kAggressiveCacheDiscardThreshold)
+    return base::MemoryPressureObserverChromeOS::
+        THRESHOLD_AGGRESSIVE_CACHE_DISCARD;
+  if (group_name == kAggressiveTabDiscardThreshold)
+    return base::MemoryPressureObserverChromeOS::
+        THRESHOLD_AGGRESSIVE_TAB_DISCARD;
+  if (group_name == kAggressiveThreshold)
+    return base::MemoryPressureObserverChromeOS::THRESHOLD_AGGRESSIVE;
+
+  return base::MemoryPressureObserverChromeOS::THRESHOLD_DEFAULT;
 }
 
 }  // namespace switches