[Reland] Refactor WebappRegistry into a singleton instance.

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

Index: chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
index c29dab64873e6461f20f301ad4a09a3ce2a398dd..9c5d5b0c74efe2c57d14cb98c4a7d1fd8a7ee44c 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
@@ -93,11 +93,12 @@ public class WebappModeTest extends MultiActivityTestBase {
     @Override
     public void setUp() throws Exception {
         super.setUp();
+        WebappRegistry.refreshSharedPrefsForTesting();
 
         // Register the webapps 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(
+        WebappRegistry.getInstance().register(
                 WEBAPP_1_ID, new WebappRegistry.FetchWebappDataStorageCallback() {
                     @Override
                     public void onWebappDataStorageRetrieved(WebappDataStorage storage) {
@@ -105,7 +106,7 @@ public class WebappModeTest extends MultiActivityTestBase {
                                 WEBAPP_1_ID, WEBAPP_1_URL, WEBAPP_1_TITLE, WEBAPP_ICON, true));
                     }
                 });
-        WebappRegistry.registerWebapp(
+        WebappRegistry.getInstance().register(
                 WEBAPP_2_ID, new WebappRegistry.FetchWebappDataStorageCallback() {
                     @Override
                     public void onWebappDataStorageRetrieved(WebappDataStorage storage) {