Update PiP dismiss target on theme change

Re-initiate the DismissCircleView upon theme change to make sure the PiP
dismiss target inherits the right theme color.

Bug: 199359063
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/bIMe3fAFoW6Nw47Ye894MZ
Test: manually, see video
Change-Id: Ia65c633fd636114ddbdc2ff497245e2cb73f7745

libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipController.java

@@ -463,6 +463,7 @@ public class PipController implements PipTransitionController.PipTransitionCallb
     }
 
     private void onOverlayChanged() {
+        mTouchHandler.onOverlayChanged();
         onDisplayChanged(new DisplayLayout(mContext, mContext.getDisplay()),
                 false /* saveRestoreSnapFraction */);
     }

libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipTouchHandler.java

@@ -259,6 +259,11 @@ public class PipTouchHandler {
         mPipDismissTargetHandler.updateMagneticTargetSize();
     }
 
+    public void onOverlayChanged() {
+        // onOverlayChanged is triggered upon theme change, update the dismiss target accordingly.
+        mPipDismissTargetHandler.init();
+    }
+
     private boolean shouldShowResizeHandle() {
         return false;
     }