[GCM Driver] Enable TokenInvalidAfterDays by default

now that it has been rolled out to 100% on Stable.

Bug: 814376
Change-Id: Ib643fcb4cea179ece647b75d07dfd3a92f935e47
Reviewed-on: https://chromium-review.googlesource.com/1069091Reviewed-by: Peter Beverloo <peter@chromium.org>
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561012}

components/gcm_driver/features.cc

@@ -15,7 +15,7 @@ namespace gcm {
 namespace features {
 
 const base::Feature kInvalidateTokenFeature{"GCMTokenInvalidAfterDays",
-                                            base::FEATURE_DISABLED_BY_DEFAULT};
+                                            base::FEATURE_ENABLED_BY_DEFAULT};
 const char kParamNameTokenInvalidationPeriodDays[] =
     "token_invalidation_period";
 // A token invalidation period of 0 means the feature is disabled, and the