Add tests to make sure closed CCT activities are not leaked.

base/android/java/src/org/chromium/base/ThreadUtils.java

Index: base/android/java/src/org/chromium/base/ThreadUtils.java
diff --git a/base/android/java/src/org/chromium/base/ThreadUtils.java b/base/android/java/src/org/chromium/base/ThreadUtils.java
index 771fab3ac45fd152fcadaac7d7a865ab0d9d35db..1c9e2401e11cd79acdd474a98d7f69c5bd9853fa 100644
--- a/base/android/java/src/org/chromium/base/ThreadUtils.java
+++ b/base/android/java/src/org/chromium/base/ThreadUtils.java
@@ -49,7 +49,8 @@ public class ThreadUtils {
         }
     }
 
-    private static Handler getUiThreadHandler() {
+    /** Returns the underlying UI thread handler. */
+    public static Handler getUiThreadHandler() {
         synchronized (sLock) {
             if (sUiThreadHandler == null) {
                 if (sWillOverride) {