Disable snap targets that make apps <220dp

- Make minimal task size 220dp.
- Disable upper and lower targets if they result in less
than 220dp task size.
- If even the middle target doesn't allow 220dp task size,
disable entering split screen altogether.

Bug: 26451260
Change-Id: I06e358c9b3da0172c5def75cdadf975f87f9fa57
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index 8395083..d34e8fc 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -3249,13 +3249,9 @@
     }
 
     private void calculateDefaultMinimalSizeOfResizeableTasks(ActivityDisplay display) {
-        if (display.mDisplayId != Display.DEFAULT_DISPLAY) {
-            return;
-        }
-        final float fraction = mService.mContext.getResources().getFraction(com.android.internal.R.
-                fraction.config_displayFractionForDefaultMinimalSizeOfResizeableTask, 1, 1);
-        mDefaultMinimalSizeOfResizeableTask = (int) (fraction * Math.min(
-                display.mDisplayInfo.logicalWidth, display.mDisplayInfo.logicalHeight));
+        mDefaultMinimalSizeOfResizeableTask =
+                mService.mContext.getResources().getDimensionPixelSize(
+                        com.android.internal.R.dimen.default_minimal_size_resizable_task);
     }
 
     private void handleDisplayRemoved(int displayId) {