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 199 matching lines @@
 // 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.
 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 69 matching lines @@
 
 // Enable automatic timezone update.
 const char kEnableTimeZoneTrackingOption[] = "enable-timezone-tracking-option";
 
 bool WakeOnWifiEnabled() {
   return !base::CommandLine::ForCurrentProcess()->HasSwitch(kDisableWakeOnWifi);
 }
 
 base::MemoryPressureObserverChromeOS::MemoryPressureThresholds
 GetMemoryPressureThresholds() {
-  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
-          kMemoryPressureThresholds)) {

[Mr4D (OOO till 08-26), 2015/02/09 00:54:54]

The field trial code should go into the case that there is no switch specified.

The order is:
1. User settings are most important -> they cannot be overwritten.
2. Trials can be used if 1. does not exist.

-    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