Adjust notification paddings

- Reduce main notification height
- Increase header height and center "Notifications"
- Footer has short height when empty to serve as padding

Bug: 65215656
Change-Id: I691d176628b0b51e8d9af030084b8c29837778dc
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 3f6efd7..b1f9d63 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -214,9 +214,11 @@
     <dimen name="notification_padding_end">12dp</dimen>
     <!-- notification_padding_end + (icon_size - footer_icon_size) / 2 -->
     <dimen name="notification_footer_icon_row_padding">15dp</dimen>
-    <dimen name="notification_header_height">32dp</dimen>
-    <dimen name="notification_main_height">96dp</dimen>
+    <dimen name="notification_header_height">36dp</dimen>
+    <dimen name="notification_main_height">84dp</dimen>
     <dimen name="notification_footer_height">32dp</dimen>
+    <!-- How much space to keep as padding for the last notification when the footer collapses -->
+    <dimen name="notification_empty_footer_height">6dp</dimen>
     <dimen name="notification_header_text_size">13sp</dimen>
     <dimen name="notification_header_count_text_size">12sp</dimen>
     <dimen name="notification_main_title_size">16sp</dimen>