[WebLayer] Use ApiHelper instead of calling the R API directly

Forgot to use ApiHelperForR for getMaxmiumWindowMetrics() the last time
in http://crrev/c/3192314

Bug: 1241568
Change-Id: I7137493d2c63e80d84087d972d2ebad9150bb3e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3206538
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Commit-Queue: Shimi Zhang <ctzsm@chromium.org>
Auto-Submit: Shimi Zhang <ctzsm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#928404}

weblayer/shell/android/shell_apk/src/org/chromium/weblayer/shell/WebLayerShellActivity.java

@@ -49,6 +49,7 @@
 import androidx.fragment.app.FragmentTransaction;
 
 import org.chromium.base.IntentUtils;
+import org.chromium.base.compat.ApiHelperForR;
 import org.chromium.weblayer.Browser;
 import org.chromium.weblayer.BrowsingDataType;
 import org.chromium.weblayer.ContextMenuParams;
@@ -940,7 +941,7 @@ private Point getDisplaySize() {
         Point point = new Point();
         WindowManager windowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
-            Rect rect = windowManager.getMaximumWindowMetrics().getBounds();
+            Rect rect = ApiHelperForR.getMaximumWindowMetricsBounds(windowManager);
             point.set(rect.width(), rect.height());
         } else {
             Display display = windowManager.getDefaultDisplay();