Fixing test due to null PiP default bounds.

- Also moving the default bounds call into the pinned stack window
  controller

Bug: 37682538
Test: bit FrameworksServicesTests:com.android.server.am.ActivityStackSupervisorTests\#testReplacingTaskInPinnedStack

Change-Id: Id6608d484617ec1a596e608aab649a082b4b1e95
diff --git a/services/core/java/com/android/server/am/PinnedActivityStack.java b/services/core/java/com/android/server/am/PinnedActivityStack.java
index a4932bb..672f563 100644
--- a/services/core/java/com/android/server/am/PinnedActivityStack.java
+++ b/services/core/java/com/android/server/am/PinnedActivityStack.java
@@ -43,6 +43,11 @@
         return new PinnedStackWindowController(mStackId, this, displayId, onTop, outBounds);
     }
 
+    Rect getPictureInPictureBounds(float aspectRatio, boolean useExistingStackBounds) {
+        return getWindowContainerController().getPictureInPictureBounds(aspectRatio,
+                useExistingStackBounds);
+    }
+
     void animateResizePinnedStack(Rect sourceHintBounds, Rect toBounds, int animationDuration,
             boolean schedulePipModeChangedOnAnimationEnd) {
         getWindowContainerController().animateResizePinnedStack(toBounds, sourceHintBounds,