Mark first frames in metrics properly

Such that we only set the flag in case window visibility actually
changes. There are a lot of other cases where we need to do a
window relayout which can lead to visible jank.

Test: FrameMetricsListenerTest, manual
Bug: 185902609
Change-Id: Ia09ce640f3a89bf9dd4ff0f4e4469e88a513709a
diff --git a/libs/hwui/FrameInfo.h b/libs/hwui/FrameInfo.h
index 2a134fa..540a88b 100644
--- a/libs/hwui/FrameInfo.h
+++ b/libs/hwui/FrameInfo.h
@@ -68,7 +68,7 @@
 
 namespace FrameInfoFlags {
 enum {
-    WindowLayoutChanged = 1 << 0,
+    WindowVisibilityChanged = 1 << 0,
     RTAnimation = 1 << 1,
     SurfaceCanvas = 1 << 2,
     SkippedFrame = 1 << 3,