Enable Purge+throttle by default except Android and MacOS.

content/public/common/content_features.cc

 // Copyright 2015 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 "build/build_config.h"
 #include "content/public/common/content_features.h"
 
 namespace features {
 
 // All features in alphabetical order.
@@ skipping 132 matching lines @@
 
 // Whether we should force a touchstart and first touchmove per scroll event
 // listeners to be non-blocking during fling.
 const base::Feature kPassiveEventListenersDueToFling{
     "PassiveEventListenersDueToFling", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Pointer events support.
 const base::Feature kPointerEvents{"PointerEvent",
                                    base::FEATURE_ENABLED_BY_DEFAULT};
 
-// Enables purge and suspend.
-const base::Feature kPurgeAndSuspend{"PurgeAndSuspend",
-                                     base::FEATURE_DISABLED_BY_DEFAULT};
+// Enables Purge+Throttle on platforms except Android and MacOS.
+// (Android) Purge+Throttle depends on TabManager, but TabManager doesn't
+// support Android. Enable after Android is supported.
+// (MacOS X) Enable after Purge+Throttle handles memory pressure signals
+// send by OS correctly.
+const base::Feature kPurgeAndSuspend {
+  "PurgeAndSuspend",
+#if defined(OS_MACOSX) || defined(OS_ANDROID)
+      base::FEATURE_DISABLED_BY_DEFAULT
+#else
+      base::FEATURE_ENABLED_BY_DEFAULT
+#endif
+};
 
 // RAF aligned mouse input events support.
 const base::Feature kRafAlignedMouseInputEvents{
     "RafAlignedMouseInput", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // RAF aligned touch input events support.
 const base::Feature kRafAlignedTouchInputEvents{
     "RafAlignedTouchInput", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // If Pepper 3D Image Chromium is allowed, this feature controls whether it is
@@ skipping 123 matching lines @@
 #endif  // !defined(OS_ANDROID)
 
 #if defined(OS_WIN)
 // Emergency "off switch" for new Windows sandbox security mitigation,
 // sandbox::MITIGATION_EXTENSION_POINT_DISABLE.
 const base::Feature kWinSboxDisableExtensionPoints{
     "WinSboxDisableExtensionPoint", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 }  // namespace features