Use an MutationObserver to check when a password form disappears after XHR

third_party/WebKit/public/web/modules/password_manager/WebFormElementObserver.h

Index: third_party/WebKit/public/web/modules/password_manager/WebFormElementObserver.h
diff --git a/third_party/WebKit/public/web/modules/password_manager/WebFormElementObserver.h b/third_party/WebKit/public/web/modules/password_manager/WebFormElementObserver.h
new file mode 100644
index 0000000000000000000000000000000000000000..0bfd2deb73bc732fb395ee9e1300178ceeb9d0bc
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+++ b/third_party/WebKit/public/web/modules/password_manager/WebFormElementObserver.h
@@ -0,0 +1,38 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WebFormElementObserver_h
+#define WebFormElementObserver_h
+
+#include <memory>
+
+#include "public/platform/WebCommon.h"
+
+namespace blink {
+
+class WebFormElement;
+class WebFormElementObserverCallback;
+class WebInputElement;
+
+class BLINK_EXPORT WebFormElementObserver {
+ public:
+  // Creates a WebFormElementObserver. Delete this WebFormElementObsrver by
+  // calling WebFormElementObserver::Disconnect.
+  static WebFormElementObserver* Create(
+      WebFormElement&,
+      std::unique_ptr<WebFormElementObserverCallback>);
+  static WebFormElementObserver* Create(
+      WebInputElement&,
+      std::unique_ptr<WebFormElementObserverCallback>);
+
+  virtual void Disconnect() = 0;
+
+ protected:
+  WebFormElementObserver() = default;
+  virtual ~WebFormElementObserver() = default;
+};
+
+}  // namespace blink
+
+#endif  // WebFormElementObserver_h