Enabling "in test harness" flag with a direct call

This allows running in-proc tests without enabling test harness on
Android and restarting Launcher.

Bug: 110103162
Test: TaplTests
Change-Id: Ife44eff4760eb1349a10847efe2c1f27643bf146
diff --git a/src/com/android/launcher3/Utilities.java b/src/com/android/launcher3/Utilities.java
index 74fc8d1..231c4b7 100644
--- a/src/com/android/launcher3/Utilities.java
+++ b/src/com/android/launcher3/Utilities.java
@@ -136,9 +136,13 @@
             CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE,
             TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
 
-    public static final boolean IS_RUNNING_IN_TEST_HARNESS =
+    public static boolean IS_RUNNING_IN_TEST_HARNESS =
                     ActivityManager.isRunningInTestHarness();
 
+    public static void enableRunningInTestHarnessForTests() {
+        IS_RUNNING_IN_TEST_HARNESS = true;
+    }
+
     public static boolean isPropertyEnabled(String propertyName) {
         return Log.isLoggable(propertyName, Log.VERBOSE);
     }