Make sure test package is fully stopped before starting test

Also allow for a slight delay before checking that the test activity
is resumed.

Bug: 29385449
Change-Id: I563456fe22bef003e447895c5243356d6c870f31
diff --git a/hostsidetests/services/windowmanager/src/android/wm/cts/CrossAppDragAndDropTests.java b/hostsidetests/services/windowmanager/src/android/wm/cts/CrossAppDragAndDropTests.java
index ee8602c..8fc3264 100644
--- a/hostsidetests/services/windowmanager/src/android/wm/cts/CrossAppDragAndDropTests.java
+++ b/hostsidetests/services/windowmanager/src/android/wm/cts/CrossAppDragAndDropTests.java
@@ -146,6 +146,7 @@
         // WindowManagerService#mDockedStackCreateBounds.
         executeShellCommand(getMoveTaskCommand(taskId, DOCKED_STACK_ID));
         waitForResume(mSourcePackageName, SOURCE_ACTIVITY_NAME);
+        executeShellCommand(AM_FORCE_STOP + SOURCE_PACKAGE_NAME);
 
         // Remove special stacks.
         executeShellCommand(AM_REMOVE_STACK + PINNED_STACK_ID);
@@ -174,6 +175,7 @@
         final String fullActivityName = packageName + "." + activityName;
         int retryCount = 3;
         do {
+            Thread.sleep(500);
             String logs = executeShellCommand("logcat -d -b events");
             for (String line : logs.split("\\n")) {
                 if(line.contains("am_on_resume_called") && line.contains(fullActivityName)) {