Revert of [Reland] Refactor WebappRegistry into a singleton instance.

chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappActivityTestBase.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappActivityTestBase.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappActivityTestBase.java b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappActivityTestBase.java
index e63b80f5f4cd68e990db62e09173a9e072aad64e..ec1f26a1bd1fb623e199c01278aef335753d9c5c 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappActivityTestBase.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappActivityTestBase.java
@@ -92,12 +92,16 @@
     protected void setUp() throws Exception {
         super.setUp();
 
-        // Register the webapp so when the data storage is opened, the test doesn't crash.
-        WebappRegistry.refreshSharedPrefsForTesting();
-        TestFetchStorageCallback callback = new TestFetchStorageCallback();
-        WebappRegistry.getInstance().register(WEBAPP_ID, callback);
-        callback.waitForCallback(0);
-        callback.getStorage().updateFromShortcutIntent(createIntent());
+        // Register the webapp so when the data storage is opened, the test doesn't crash. There is
+        // no race condition with the retrieval as AsyncTasks are run sequentially on the background
+        // thread.
+        WebappRegistry.registerWebapp(
+                WEBAPP_ID, new WebappRegistry.FetchWebappDataStorageCallback() {
+                    @Override
+                    public void onWebappDataStorageRetrieved(WebappDataStorage storage) {
+                        storage.updateFromShortcutIntent(createIntent());
+                    }
+                });
     }
 
     /**