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

chromeos/chromeos_switches.cc

 // Copyright (c) 2012 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 "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
 
 namespace chromeos {
 namespace switches {
 
 // Path for app's OEM manifest file.
 const char kAppOemManifestFile[] = "app-mode-oem-manifest";
 
@@ skipping 196 matching lines @@
 // Specifies the profile to use once a chromeos user is logged in.
 // This parameter is ignored if user goes through login screen since user_id
 // hash defines which profile directory to use.
 // In case of browser restart within active session this parameter is used
 // to pass user_id hash for primary user.
 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";
 
 // Skips all other OOBE pages after user login.
 const char kOobeSkipPostLogin[] = "oobe-skip-postlogin";
 
 // Disable GAIA services such as enrollment and OAuth session restore. Used by
 // 'fake' telemetry login.
 const char kDisableGaiaServices[] = "disable-gaia-services";
@@ skipping 68 matching lines @@
     "enable-captive-portal-bypass-proxy";
 
 // Disable automatic timezone update.
 const char kDisableTimeZoneTrackingOption[] =
     "disable-timezone-tracking-option";
 
 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
 }  // namespace chromeos