Reparent surface control for Webview overlay

When the root surface control changes, the parent of the Webview surface control must be changed.

Bug: 191900007
Test: switch app, or turn on/off screen
Change-Id: Ib7b34133776fd5944afc638bfee471afe6a17349
diff --git a/libs/hwui/WebViewFunctorManager.h b/libs/hwui/WebViewFunctorManager.h
index a84cda5..048d1fb 100644
--- a/libs/hwui/WebViewFunctorManager.h
+++ b/libs/hwui/WebViewFunctorManager.h
@@ -85,12 +85,16 @@
     }
 
 private:
+    void reparentSurfaceControl(ASurfaceControl* parent);
+
+private:
     WebViewFunctorCallbacks mCallbacks;
     void* const mData;
     int mFunctor;
     RenderMode mMode;
     bool mHasContext = false;
     bool mCreatedHandle = false;
+    int32_t mParentSurfaceControlGenerationId = 0;
     ASurfaceControl* mSurfaceControl = nullptr;
 };