Add taskbarIconSize to GridOption/DisplayOptions

- Renamed variables to make it more clear what they represent
- DeviceProfile will be source of truth for taskbar
  sizes

Bug: 265144213
Test: phone, multi-display, tablet
Change-Id: Id9c19d15a65894fd7645e0f876a4b6527b713c34
Flag: ENABLE_TRANSIENT_TASKBAR=true
diff --git a/res/values/config.xml b/res/values/config.xml
index e13b51c..5a6698b 100644
--- a/res/values/config.xml
+++ b/res/values/config.xml
@@ -164,6 +164,10 @@
     <item name="swipe_up_rect_xy_damping_ratio" type="dimen" format="float">0.8</item>
     <item name="swipe_up_rect_xy_stiffness" type="dimen" format="float">200</item>
 
+    <!-- Taskbar -->
+    <!-- This is a float because it is converted to dp later in DeviceProfile -->
+    <item name="taskbar_icon_size" type="dimen" format="float">0</item>
+
     <!-- These params are only used for hotseat items on devices that have a taskbar. -->
     <item name="taskbar_swipe_up_rect_x_stiffness" type="dimen" format="float">350</item>
     <item name="taskbar_swipe_up_rect_x_damping" type="dimen" format="float">0.9</item>