Add feature flag for notification triggers.

This adds a disabled by default flag for the notification trigger feature.
It will be used by crrev.com/c/1477840 to guard the implementation.

Bug: 891339
Change-Id: I7a11549b49bfcb56bafd5591de06d301de5c5b2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1505460
Commit-Queue: Richard Knoll <knollr@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638589}

content/public/common/content_features.cc

@@ -294,6 +294,10 @@ const base::Feature kNetworkServiceInProcess{"NetworkServiceInProcess",
 const base::Feature kNotificationContentImage{"NotificationContentImage",
                                               base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Enables the notification trigger API.
+const base::Feature kNotificationTriggers{"NotificationTriggers",
+                                          base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Origin Policy. See https://crbug.com/751996
 const base::Feature kOriginPolicy{"OriginPolicy",
                                   base::FEATURE_DISABLED_BY_DEFAULT};

content/public/common/content_features.h

@@ -74,6 +74,7 @@ CONTENT_EXPORT extern const base::Feature kMojoVideoCaptureSecondary;
 CONTENT_EXPORT extern const base::Feature kNetworkQualityEstimatorWebHoldback;
 CONTENT_EXPORT extern const base::Feature kNetworkServiceInProcess;
 CONTENT_EXPORT extern const base::Feature kNotificationContentImage;
+CONTENT_EXPORT extern const base::Feature kNotificationTriggers;
 CONTENT_EXPORT extern const base::Feature kOriginPolicy;
 CONTENT_EXPORT extern const base::Feature kOriginTrials;
 CONTENT_EXPORT extern const base::Feature kOverscrollHistoryNavigation;