[App banners] Start adding unit tets

chrome/android/java/src/org/chromium/chrome/browser/Tab.java

Index: chrome/android/java/src/org/chromium/chrome/browser/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
index 9be08415fa321f93484351fd098b951e56eddd4d..5e399f1c794bd7a4372c8a45e94c4086a0552355 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
@@ -2441,6 +2441,14 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
     }
 
     /**
+     * @return the AppBannerManager.
+     */
+    @VisibleForTesting
+    public AppBannerManager getAppBannerManagerForTesting() {
+        return mAppBannerManager;
+    }
+
+    /**
      * Ensures the counter is at least as high as the specified value.  The counter should always
      * point to an unused ID (which will be handed out next time a request comes in).  Exposed so
      * that anything externally loading tabs and ids can set enforce new tabs start at the correct