Add a field trial to enable plugin power saver for all users.

components/content_settings/core/browser/plugins_field_trial.h

Index: components/content_settings/core/browser/plugins_field_trial.h
diff --git a/components/content_settings/core/browser/plugins_field_trial.h b/components/content_settings/core/browser/plugins_field_trial.h
index ccc39dfb42ab5c7cc9afd9970aa3e93bd0c6fc1f..eb7269cf07338e22540431831a8b97651aec6089 100644
--- a/components/content_settings/core/browser/plugins_field_trial.h
+++ b/components/content_settings/core/browser/plugins_field_trial.h
@@ -14,7 +14,11 @@ namespace content_settings {
 // This class manages the Plugins field trials.
 class PluginsFieldTrial {
  public:
-  static const char kFieldTrialName[];
+  // A legacy field trial used to dogfood Plugin Power Saver. Remove soon.
+  static const char kForceFieldTrial[];
+
+  // The field trial responsible for rolling out Plugin Power Saver to users.
+  static const char kEnableFieldTrial[];
 
   // Returns the effective content setting for plugins. Passes non-plugin
   // content settings through without modification.