Add missing notifyPixelsChanged

Fixes: 63400947
Test: CTS test PixelCopyTest#testReuseBitmap
Change-Id: Iad6fe331f84415528c1858a1fdbf26bce784cd53
diff --git a/libs/hwui/OpenGLReadback.cpp b/libs/hwui/OpenGLReadback.cpp
index 19d5d9d..e798edf 100644
--- a/libs/hwui/OpenGLReadback.cpp
+++ b/libs/hwui/OpenGLReadback.cpp
@@ -238,6 +238,7 @@
         // TODO: We should convert to linear space when the target is RGBA16F
         glReadPixels(0, 0, bitmap->width(), bitmap->height(), format,
                 type, bitmap->getPixels());
+        bitmap->notifyPixelsChanged();
     }
 
     // Cleanup