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/renderthread/CanvasContext.cpp b/libs/hwui/renderthread/CanvasContext.cpp
index 0c9711b..81cee61 100644
--- a/libs/hwui/renderthread/CanvasContext.cpp
+++ b/libs/hwui/renderthread/CanvasContext.cpp
@@ -201,6 +201,7 @@
         funcs.releaseFunc(mSurfaceControl);
     }
     mSurfaceControl = surfaceControl;
+    mSurfaceControlGenerationId++;
     mExpectSurfaceStats = surfaceControl != nullptr;
     if (mSurfaceControl != nullptr) {
         funcs.acquireFunc(mSurfaceControl);