Wait for all window transitions to finish in CTS

In ActivityManagerActivityVisiblityTests#testVisibleBehindHomeActivity
on devices that doesn't support leanback we were not waiting long enough
for the VisibleBehindHomeActivity to go away.

Bug: 28786255
Change-Id: I9c2b292ee0cf98ec855ea0bd219b71c5518a3be6
diff --git a/hostsidetests/services/activitymanager/src/android/server/cts/WindowManagerState.java b/hostsidetests/services/activitymanager/src/android/server/cts/WindowManagerState.java
index 7ecdcb6..3122a2e 100644
--- a/hostsidetests/services/activitymanager/src/android/server/cts/WindowManagerState.java
+++ b/hostsidetests/services/activitymanager/src/android/server/cts/WindowManagerState.java
@@ -143,10 +143,9 @@
             if (ws != null) {
                 log(ws.toString());
 
-                if (visibleOnly && mWindows.isEmpty()) {
-                    // This is the front window. Check to see if we are in the middle of
-                    // transitioning. If we are, we want to skip dumping until window manager is
-                    // done transitioning the top window.
+                if (visibleOnly) {
+                    // Check to see if we are in the middle of transitioning. If we are, we want to
+                    // skip dumping until window manager is done transitioning windows.
                     if (ws.isStartingWindow()) {
                         log("Skipping dump due to starting window transition...");
                         return;