Animate SplitPlaceholderView when entering split from overview

Bugs tracked in b/181704764

Bug: 181704764
Test: Tested on phone and large screen in multiple orientations

Change-Id: I07509006ae3d1f4425dc5119d0c8ed52b41a3bc2
diff --git a/res/layout/floating_split_select_view.xml b/res/layout/floating_split_select_view.xml
new file mode 100644
index 0000000..e184b91
--- /dev/null
+++ b/res/layout/floating_split_select_view.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<com.android.quickstep.views.FloatingTaskView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <ImageView
+        android:id="@+id/thumbnail"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:visibility="gone" />
+
+    <com.android.quickstep.views.SplitPlaceholderView
+        android:id="@+id/split_placeholder"
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/split_placeholder_size"
+        android:background="@android:color/white"
+        android:visibility="gone" />
+
+</com.android.quickstep.views.FloatingTaskView>
\ No newline at end of file
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 46570f0..dd27685 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -326,6 +326,7 @@
     <dimen name="overview_task_margin">0dp</dimen>
     <dimen name="overview_actions_bottom_margin_gesture">0dp</dimen>
     <dimen name="overview_actions_bottom_margin_three_button">0dp</dimen>
+    <dimen name="split_placeholder_size">110dp</dimen>
 
 <!-- Workspace grid visualization parameters -->
     <dimen name="grid_visualization_rounding_radius">22dp</dimen>