Allow mocking package local stuff

Test: Tested in depending CL
Change-Id: If3a794fe6cc21b99c7b02a6af52d9d9c1027c0ae
diff --git a/services/tests/servicestests/src/com/android/server/wm/WindowTestsBase.java b/services/tests/servicestests/src/com/android/server/wm/WindowTestsBase.java
index 56a3fb0..b8e8946 100644
--- a/services/tests/servicestests/src/com/android/server/wm/WindowTestsBase.java
+++ b/services/tests/servicestests/src/com/android/server/wm/WindowTestsBase.java
@@ -89,6 +89,9 @@
     public void setUp() throws Exception {
         if (!sOneTimeSetupDone) {
             sOneTimeSetupDone = true;
+
+            // Allows to mock package local classes and methods
+            System.setProperty("dexmaker.share_classloader", "true");
             MockitoAnnotations.initMocks(this);
         }