Store URLs in WebappDataStorage, and purge them when history is cleared.

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 a96654745cc01b761a7841216721e0abccf797ca..132db68e057a1a95ec2017bca6ecde52a1a70f14 100644
--- a/chrome/browser/browsing_data/browsing_data_remover_unittest.cc
+++ b/chrome/browser/browsing_data/browsing_data_remover_unittest.cc
@@ -274,6 +274,12 @@ class TestWebappRegistry : public WebappRegistry {
     BrowserThread::PostDelayedTask(BrowserThread::UI, FROM_HERE, callback,
                                    base::TimeDelta::FromMilliseconds(10));
   }
+
+  void ClearWebappHistory(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));
+  }
 };
 #endif