Normalize bar icon size and alignment

shell/plugins/panels/dropbox/DropboxIcon.qml

@@ -7,11 +7,13 @@ Item {
   id: root
 
   property real iconSize: Style.font.icon
+  readonly property real aspectRatio: 1.18
+  property real artworkScale: 0.95
   property color color: Commons.Color.foreground
 
-  width: iconSize * 1.18
+  width: iconSize * aspectRatio
   height: iconSize
-  implicitWidth: iconSize * 1.18
+  implicitWidth: iconSize * aspectRatio
   implicitHeight: iconSize
 
   Shape {
@@ -19,7 +21,7 @@ Item {
     antialiasing: true
     layer.enabled: true
     layer.samples: 4
-    scale: 0.95
+    scale: root.artworkScale
 
     Tile { cx: root.width * 0.25; cy: root.height * 0.188 }
     Tile { cx: root.width * 0.75; cy: root.height * 0.188 }

shell/plugins/panels/dropbox/Panel.qml

@@ -175,8 +175,10 @@ Panel {
     iconComponent: Component {
       Item {
         DropboxIcon {
-          anchors.centerIn: parent
-          iconSize: Style.space(12)
+          x: (parent.width - width) / 2
+          y: (parent.height - height) / 2
+          iconSize: button.iconSize / aspectRatio
+          artworkScale: 1
           color: root.barIconColor
           opacity: dropbox.active ? 1.0 : 0.6
         }