make --enable-native-notifications a feature

BUG=571056

Review-Url: https://codereview.chromium.org/2429783002
Cr-Commit-Position: refs/heads/master@{#426009}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index e9bf8c06..c2b5d9cf 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1285,7 +1285,7 @@
 #if defined(OS_MACOSX)
     {"enable-native-notifications", IDS_NOTIFICATIONS_NATIVE_FLAG,
      IDS_NOTIFICATIONS_NATIVE_FLAG_DESCRIPTION, kOsMac,
-     SINGLE_VALUE_TYPE(switches::kEnableNativeNotifications)},
+     FEATURE_VALUE_TYPE(features::kNativeNotifications)},
 #endif  // OS_MACOSX
 #if defined(TOOLKIT_VIEWS)
     {"disable-views-rect-based-targeting",
@@ -2042,7 +2042,7 @@
      IDS_FLAGS_EXPENSIVE_BACKGROUND_TIMER_THROTTLING_NAME,
      IDS_FLAGS_EXPENSIVE_BACKGROUND_TIMER_THROTTLING_DESCRIPTION, kOsAll,
      FEATURE_VALUE_TYPE(features::kExpensiveBackgroundTimerThrottling)},
-     {"security-chip", IDS_FLAGS_SECURITY_CHIP_NAME,
+    {"security-chip", IDS_FLAGS_SECURITY_CHIP_NAME,
      IDS_FLAGS_SECURITY_CHIP_DESCRIPTION, kOsDesktop,
      MULTI_VALUE_TYPE(kSecurityChipChoices)},
     {"security-chip-animation", IDS_FLAGS_SECURITY_CHIP_ANIMATION_NAME,