[Sync] Remove static methods on SyncedWindowDelegate.

chrome/browser/sync/sessions/session_data_type_controller_unittest.cc

Index: chrome/browser/sync/sessions/session_data_type_controller_unittest.cc
diff --git a/chrome/browser/sync/sessions/session_data_type_controller_unittest.cc b/chrome/browser/sync/sessions/session_data_type_controller_unittest.cc
index 77b4ee7c2675d336744f7ebc1d8990df87935141..06cec7cb4260568755f180dcd30c43d8c98e6f67 100644
--- a/chrome/browser/sync/sessions/session_data_type_controller_unittest.cc
+++ b/chrome/browser/sync/sessions/session_data_type_controller_unittest.cc
@@ -72,6 +72,10 @@ class MockSyncedWindowDelegatesGetter : public SyncedWindowDelegatesGetter {
     return delegates_;
   }
 
+  const SyncedWindowDelegate* FindById(SessionID::id_type id) override {
+    return nullptr;
+  }
+
   void Add(SyncedWindowDelegate* delegate) {
     delegates_.insert(delegate);
   }