Revert "[applets/notifications] Move "Clear History" action out of burger menu"

This reverts commit 58935741.

The approach taken in this commit was sub-optimal and not consistent
with what we do for other applets, so it needs to be re-thought.

applets/notifications/package/contents/ui/FullRepresentation.qml

@@ -173,18 +173,15 @@ PlasmaComponents3.Page {
                 }
 
                 PlasmaComponents3.ToolButton {
-                    // TODO: Conditionalize visiblity again once support is added
-                    // in plasma-framework for showing more than one action on the
-                    // header so the clear button isn't always in the hamburger menu
+                    visible: !(plasmoid.containmentDisplayHints & PlasmaCore.Types.ContainmentDrawsPlasmoidHeading)
 
-                    text: i18nc("Clear all notifications", "Clear All")
+                    Accessible.name: plasmoid.action("clearHistory").text
                     icon.name: "edit-clear-history"
-                    enabled: historyModel.expiredNotificationsCount > 0
-                    onClicked: {
-                        historyModel.clear(NotificationManager.Notifications.ClearExpired);
-                        if (historyModel.count === 0) {
-                            root.closePassivePlasmoid();
-                        }
+                    enabled: plasmoid.action("clearHistory").visible
+                    onClicked: action_clearHistory()
+
+                    PlasmaComponents3.ToolTip {
+                        text: parent.Accessible.name
                     }
                 }
             }

applets/notifications/package/contents/ui/main.qml

@@ -158,6 +158,13 @@ Item {
         }
     }
 
+    function action_clearHistory() {
+        historyModel.clear(NotificationManager.Notifications.ClearExpired);
+        if (historyModel.count === 0) {
+            closePassivePlasmoid();
+        }
+    }
+
     function action_openKcm() {
         KQCAddons.KCMShell.openSystemSettings("kcm_notifications");
     }
@@ -165,6 +172,11 @@ Item {
     Component.onCompleted: {
         Globals.adopt(plasmoid);
 
+        plasmoid.setAction("clearHistory", i18n("Clear History"), "edit-clear-history");
+        var clearAction = plasmoid.action("clearHistory");
+        clearAction.visible = Qt.binding(function() {
+            return historyModel.expiredNotificationsCount > 0;
+        });
 
         // FIXME only while Multi-page KCMs are broken when embedded in plasmoid config
         plasmoid.setAction("openKcm", i18n("&Configure Event Notifications and Actions..."), "notifications");