Draw the lock screen video from the OWE lock feed

The shell drops its own player: BackgroundMedia is image-only, and the
lock loads Owe.LockFeedSurface through a Loader, so a system without the
module shows no lock video instead of losing the whole lock screen. The
feed pauses per output when the panel blanks or power saver turns on.

The lock view keeps its still effect path and darkens the feed for
legibility. QtMultimedia and the shell video pause policy are gone, and
the base package list requires owe and owe-lockfeed instead.

shell/plugins/background/Background.qml

@@ -16,7 +16,6 @@ Item {
 
   property string currentBackground: ""
   property string displayedBackground: ""
-  property int displayedReloads: 0
   property string incomingBackground: ""
   property string oldBackground: ""
   property bool finishingTransition: false
@@ -60,9 +59,6 @@ Item {
     if (instant || !displayedBackground || isVideo(path) || isVideo(displayedBackground)) {
       oldBackground = ""
       incomingBackground = ""
-      // A theme switch can replace the file behind an unchanged path, which
-      // an unchanged property would never pick up.
-      if (displayedBackground === finalPath) displayedReloads += 1
       displayedBackground = finalPath
       revealProgress = 1
       return
@@ -187,7 +183,6 @@ Item {
   }
 
   Component.onCompleted: {
-    oweStatusProc.running = true
     refreshBackground()
   }
 
@@ -237,8 +232,6 @@ Item {
         id: base
         anchors.fill: parent
         path: root.displayedBackground
-        reloads: root.displayedReloads
-        videoEnabled: false
         onReadyChanged: {
           if (ready && root.finishingTransition) {
             root.incomingBackground = ""

shell/plugins/lock/LockFeedSurface.qml

@@ -0,0 +1,11 @@
+import QtQuick
+import Owe.LockFeed
+
+// Loaded through a Loader from LockView, so a system without the module shows
+// no lock video instead of losing the whole lock screen.
+LockFeed {
+  id: root
+
+  property bool feedEnabled: true
+  active: root.feedEnabled
+}

shell/plugins/lock/LockView.qml

@@ -43,6 +43,9 @@ Item {
     ? Border.surfaceSpec("lock", "border-error", Color.lock.borderError, root.outlineThickness, "border-alpha")
     : Border.surfaceSpec("lock", "border-active", Color.lock.borderActive, root.outlineThickness, "border-alpha")
 
+  readonly property bool video: Util.isVideoPath(root.backgroundPath)
+  readonly property bool feedActive: root.video && root.loadBackground && !root.displaysBlank && !root.powerSaverActive
+
   signal submitPassword(string password)
   signal passwordTextEdited(string password)
   signal clearFailureRequested()
@@ -89,15 +92,33 @@ Item {
     BackgroundMedia {
       id: wallpaper
       anchors.fill: parent
-      path: root.loadBackground ? root.backgroundPath : ""
+      path: root.video ? "" : root.backgroundPath
       version: root.backgroundVersion
-      playbackEnabled: root.loadBackground && !root.displaysBlank && !root.powerSaverActive
+      visible: !root.video
+    }
+
+    // OWE decodes the video once and feeds these frames to every lock surface.
+    // The feed pauses when this output blanks or on battery power saver.
+    Loader {
+      id: feedLoader
+      anchors.fill: parent
+      active: root.video
+      source: "LockFeedSurface.qml"
+      visible: status === Loader.Ready
+
+      Binding {
+        target: feedLoader.item
+        property: "feedEnabled"
+        value: root.feedActive
+        when: feedLoader.item !== null
+        restoreMode: Binding.RestoreNone
+      }
     }
 
     MultiEffect {
       anchors.fill: wallpaper
-      source: wallpaper.video ? null : wallpaper
-      visible: !wallpaper.video
+      source: root.video ? null : wallpaper
+      visible: !root.video
       autoPaddingEnabled: false
       blurEnabled: root.loadBackground && wallpaper.ready
       blur: 1.0
@@ -106,11 +127,11 @@ Item {
       contrast: -0.08
     }
 
-    // Qt's video output cannot be sampled by MultiEffect on every renderer.
+    // The feed item cannot be sampled by MultiEffect on every renderer.
     // Keep video wallpapers visible and darken them slightly for legibility.
     Rectangle {
-      anchors.fill: wallpaper
-      visible: wallpaper.video
+      anchors.fill: feedLoader
+      visible: root.video
       color: "#22000000"
     }