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

third_party/WebKit/public/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/buildflag_header.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/config.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 import("//tools/grit/grit_rule.gni")
@@ skipping 479 matching lines @@
     "web/WebEmbeddedWorker.h",
     "web/WebEmbeddedWorkerStartData.h",
     "web/WebExceptionCode.h",
     "web/WebExternalPopupMenu.h",
     "web/WebExternalPopupMenuClient.h",
     "web/WebFileChooserCompletion.h",
     "web/WebFileChooserParams.h",
     "web/WebFindOptions.h",
     "web/WebFormControlElement.h",
     "web/WebFormElement.h",
+    "web/WebFormElementObserverCallback.h",
     "web/WebFrame.h",
     "web/WebFrameClient.h",
     "web/WebFrameContentDumper.h",
     "web/WebFrameLoadType.h",
     "web/WebFrameOwnerProperties.h",
     "web/WebFrameSerializer.h",
     "web/WebFrameSerializerCacheControlPolicy.h",
     "web/WebFrameSerializerClient.h",
     "web/WebFrameWidget.h",
     "web/WebHeap.h",
@@ skipping 301 matching lines @@
   sources = [
     "web/ConsoleMessageStructTraits.cpp",
     "web/ConsoleMessageStructTraits.h",
   ]
   deps = [
     ":blink_headers",
     ":mojo_bindings_shared__generator",
     "//mojo/public/cpp/bindings:struct_traits",
   ]
 }