[Reland] Refactor WebappRegistry into a singleton instance.

chrome/browser/browsing_data/browsing_data_remover_unittest.cc

Index: chrome/browser/browsing_data/browsing_data_remover_unittest.cc
diff --git a/chrome/browser/browsing_data/browsing_data_remover_unittest.cc b/chrome/browser/browsing_data/browsing_data_remover_unittest.cc
index 241034dcf96a253aa0aaf4f2a6f5335599c7b11d..3ec5f53d419bd5627e1cf19d3d6680c43f081c2d 100644
--- a/chrome/browser/browsing_data/browsing_data_remover_unittest.cc
+++ b/chrome/browser/browsing_data/browsing_data_remover_unittest.cc
@@ -317,19 +317,13 @@ class TestWebappRegistry : public WebappRegistry {
   TestWebappRegistry() : WebappRegistry() { }
 
   void UnregisterWebappsForUrls(
-      const base::Callback<bool(const GURL&)>& url_filter,
-      const base::Closure& callback) override {
-    // Mocks out a JNI call and runs the callback as a delayed task.
-    BrowserThread::PostDelayedTask(BrowserThread::UI, FROM_HERE, callback,
-                                   base::TimeDelta::FromMilliseconds(10));
+      const base::Callback<bool(const GURL&)>& url_filter) override {
+    // Mocks out a JNI call.
   }
 
   void ClearWebappHistoryForUrls(
-      const base::Callback<bool(const GURL&)>& url_filter,
-      const base::Closure& callback) override {
-    // Mocks out a JNI call and runs the callback as a delayed task.
-    BrowserThread::PostDelayedTask(BrowserThread::UI, FROM_HERE, callback,
-                                   base::TimeDelta::FromMilliseconds(10));
+      const base::Callback<bool(const GURL&)>& url_filter) override {
+    // Mocks out a JNI call.
   }
 };
 #endif