Hide ARC VPN behind a feature flag

The UI work will be completed in the M64 timeframe, so for M63 we
will require ARC VPN to be manually enabled via chrome://flags#arc-vpn

BUG=696865
TEST=manually test in both Enabled and Disabled state

Change-Id: I5e362f2437629980c69dcfcef60a11786131e986
Reviewed-on: https://chromium-review.googlesource.com/736817
Commit-Queue: Kevin Cernekee <[email protected]>
Reviewed-by: Elijah Taylor <[email protected]>
Reviewed-by: Steven Bennetts <[email protected]>
Cr-Commit-Position: refs/heads/master@{#511507}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 634fcd8..5b6bd30 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2817,6 +2817,9 @@
      flag_descriptions::kArcNativeBridgeExperimentName,
      flag_descriptions::kArcNativeBridgeExperimentDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(arc::kNativeBridgeExperimentFeature)},
+    {"arc-vpn", flag_descriptions::kArcVpnName,
+     flag_descriptions::kArcVpnDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(arc::kVpnFeature)},
 #endif  // OS_CHROMEOS
     {"enable-generic-sensor", flag_descriptions::kEnableGenericSensorName,
      flag_descriptions::kEnableGenericSensorDescription, kOsAll,