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

third_party/WebKit/Source/core/dom/Document.h

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index 04d7cdcdbc9c1b6652df120a152158b1a2b5b80d..a39f202487fc6b20e16109863765bc1e619468f9 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -108,6 +108,7 @@ class ExceptionState;
 class FloatQuad;
 class FloatRect;
 class FormController;
+class FormElementObserver;
 class FrameRequestCallback;
 class FrameView;
 class HTMLAllCollection;
@@ -1320,6 +1321,8 @@ class CORE_EXPORT Document : public ContainerNode,
 
   CoreProbeSink* GetProbeSink() final;
 
+  FormElementObserver* GetFormElementObserver();
+
  protected:
   Document(const DocumentInit&, DocumentClassFlags = kDefaultDocumentClass);
 
@@ -1687,6 +1690,8 @@ class CORE_EXPORT Document : public ContainerNode,
   mojom::EngagementLevel engagement_level_;
 
   Member<NetworkStateObserver> network_state_observer_;
+
+  Member<FormElementObserver> form_element_observer_;

[dglazkov, 2017/05/11 21:09:05]

Does it have to be a member of Document? I am primarily worried about adding
things to Document that aren't technically part of core DOM implementation.

It looks like it's instantiated on access (RAII pattern), so maybe it could be
in a separate class? IOW, could we introduce WebFormElementObserver, which wraps
the observer and then let create it in PasswordAutofillAgent, passing
WebDocument to it?

 };
 
 extern template class CORE_EXTERN_TEMPLATE_EXPORT Supplement<Document>;