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 133 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};
+const base::Feature kPurgeAndSuspend {
+  "PurgeAndSuspend",
+#if defined(OS_MACOSX) || defined(OS_ANDROID)

[Wez, 2017/03/29 23:50:55]

Is there a bug with context on why we don't enable this for Mac OS, that you
could add a comment to link to here?

[tasak, 2017/03/30 09:26:12]

Added.
So this comment looks ok?

+      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 127 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