Match window rounded corners with system rounded corners.

Use the corner radius defined in ScreenDecorationsUtils as the rounded
corner radius to keep caption rounded corner in line with other sources
of rounded corners.

Bug: 280825814
Test: Manual; open an app that uses the system rounded corners;
confirm it lines up with caption corner.

Change-Id: Id15a7173cc72a59fef73571cac281f5f08dba48f

libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java

@@ -23,7 +23,6 @@ import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
-import android.content.res.TypedArray;
 import android.graphics.Point;
 import android.graphics.PointF;
 import android.graphics.Rect;
@@ -39,6 +38,7 @@ import android.view.View;
 import android.view.ViewConfiguration;
 import android.window.WindowContainerTransaction;
 
+import com.android.internal.policy.ScreenDecorationsUtils;
 import com.android.launcher3.icons.IconProvider;
 import com.android.wm.shell.R;
 import com.android.wm.shell.ShellTaskOrganizer;
@@ -182,11 +182,8 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
         mRelayoutParams.mShadowRadiusId = shadowRadiusID;
         mRelayoutParams.mApplyStartTransactionOnDraw = applyStartTransactionOnDraw;
 
-        final TypedArray ta = mContext.obtainStyledAttributes(
-                new int[]{android.R.attr.dialogCornerRadius});
-        mRelayoutParams.mCornerRadius = ta.getDimensionPixelSize(0, 0);
-        ta.recycle();
-
+        mRelayoutParams.mCornerRadius =
+                (int) ScreenDecorationsUtils.getWindowCornerRadius(mContext);
         relayout(mRelayoutParams, startT, finishT, wct, oldRootView, mResult);
         // After this line, mTaskInfo is up-to-date and should be used instead of taskInfo