Simplifying app icon popup

> Using a single linearLayout instead of multiple nested views
> Using clipToOutline for rounded corners instead of using canvas.saveLayer
> Removing nested view elevations and overdraw
> Using LayoutTransition for animating layout changes, instead of manually creating animators

Change-Id: I8e57092f52ca5a032a2756594fdd39788acc5a0d
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 957ec19..378249b 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -179,6 +179,7 @@
     <dimen name="deep_shortcut_drag_handle_size">16dp</dimen>
     <dimen name="popup_padding_start">10dp</dimen>
     <dimen name="popup_padding_end">16dp</dimen>
+    <dimen name="popup_vertical_padding">4dp</dimen>
     <dimen name="popup_arrow_width">10dp</dimen>
     <dimen name="popup_arrow_height">8dp</dimen>
     <dimen name="popup_arrow_vertical_offset">-2dp</dimen>
@@ -226,7 +227,6 @@
     <dimen name="notification_footer_icon_size">18dp</dimen>
     <!-- notification_icon_size + notification_padding_end + 16dp padding between icon and text -->
     <dimen name="notification_main_text_padding_end">52dp</dimen>
-    <dimen name="notification_elevation">2dp</dimen>
     <dimen name="horizontal_ellipsis_size">18dp</dimen>
     <!-- arrow_horizontal_offset_start - (ellipsis_size - arrow_width) / 2 -->
     <dimen name="horizontal_ellipsis_offset">19dp</dimen>
diff --git a/res/values/styles.xml b/res/values/styles.xml
index 8129e81..8cc4743 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -136,13 +136,6 @@
     <style name="PopupItem">
         <item name="android:colorControlHighlight">?attr/popupColorTertiary</item>
     </style>
-    <style name="PopupGutter">
-        <item name="android:backgroundTintMode">multiply</item>
-        <item name="android:backgroundTint">?attr/popupColorSecondary</item>
-        <item name="android:background">@drawable/gutter_horizontal</item>
-        <item name="android:elevation">@dimen/notification_elevation</item>
-        <item name="android:outlineProvider">none</item>
-    </style>
 
     <!-- Drop targets -->
     <style name="DropTargetButtonBase">