[Password manager] Recognise squashed login+sign-up forms

components/autofill/core/common/password_form.h

 // Copyright 2013 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 COMPONENTS_AUTOFILL_CORE_COMMON_PASSWORD_FORM_H__
 #define COMPONENTS_AUTOFILL_CORE_COMMON_PASSWORD_FORM_H__
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 41 matching lines @@
   // using basic or digest schemes. Default is SCHEME_HTML. Only PasswordForms
   // of the same Scheme will be matched/autofilled against each other.
   enum Scheme {
     SCHEME_HTML,
     SCHEME_BASIC,
     SCHEME_DIGEST,
     SCHEME_OTHER,
     SCHEME_LAST = SCHEME_OTHER
   } scheme;
 
+  // A layout characterises the sequence of non-password text and password input
+  // fields of which the form is made. It is defined as a regular language over
+  // the alphabet {N, P} (indicating Non-password and Password fields); e.g., a
+  // layout NPN+PP characterises all forms which have a single non-password
+  // field followed by a single password field, followed by 1 or more
+  // non-password fields, followed by 2 password fields.
+  // For most forms we do not care about the layout (those have LAYOUT_OTHER),
+  // but for special cases we might need to know it: e.g., the NPN+PP forms can
+  // be a login form glued to a sign-up form, and the "N+" part is what
+  // distinguishes such forms from change-password forms.
+  // A layout is useful for understanding parsed forms and deciding whether to
+  // fill them, but it is not stored.

[Garrett Casto, 2015/03/17 22:49:37]

This comment seems like more information than is necessary. Consumers of this
data don't necessarily need to care about exactly how exactly the form is laid
out for a form to be classified as LAYOUT_LOGIN_AND_SIGNUP, they just need to
know what it means. I would drop the discussion of regular expression and what
sequence needs to be matched and just talk generally about how these forms are
different.

If you want to keep technical discussion about how we determine Layout, keeping
it in PasswordFormConversionUtils seems more reasonable. Some discussion about
how we determined the current regexp seems like it could be useful (e.g. didn't
use ".*PN+P.*" since it would match signup forms which use password fields to
store private but non-password data).

[vabr (Chromium), 2015/03/18 16:51:03]

Good point, I tried to rephrase.

+  enum class Layout {
+    LAYOUT_OTHER,
+    LAYOUT_LOGIN_AND_SIGNUP,  // NPN+PP
+    LAYOUT_LAST = LAYOUT_LOGIN_AND_SIGNUP
+  };
+
   // The "Realm" for the sign-on. This is scheme, host, port for SCHEME_HTML.
   // Dialog based forms also contain the HTTP realm. Android based forms will
   // contain a string of the form "android://<hash of cert>@<package name>"
   //
   // The signon_realm is effectively the primary key used for retrieving
   // data from the database, so it must not be empty.
   std::string signon_realm;
 
   // The original "Realm" for the sign-on (scheme, host, port for SCHEME_HTML,
   // and contains the HTTP realm for dialog-based forms). This realm is only set
@@ skipping 159 matching lines @@
   GURL avatar_url;
 
   // The URL of identity provider used for federated login.
   GURL federation_url;
 
   // If true, Chrome will not return this credential to a site in response to
   // 'navigator.credentials.request()' without user interaction.
   // Once user selects this credential the flag is reseted.
   bool skip_zero_click;
 
+  // The layout as determined during parsing. Default value is LAYOUT_OTHER.
+  Layout layout;
+
   // Returns true if this match was found using public suffix matching.
   bool IsPublicSuffixMatch() const;
 
   // Equality operators for testing.
   bool operator==(const PasswordForm& form) const;
   bool operator!=(const PasswordForm& form) const;
 
   PasswordForm();
   ~PasswordForm();
 };
 
 // Map username to PasswordForm* for convenience. See password_form_manager.h.
 typedef std::map<base::string16, PasswordForm*> PasswordFormMap;
 
 typedef std::map<base::string16, const PasswordForm*> ConstPasswordFormMap;
 
 // For testing.
+std::ostream& operator<<(std::ostream& os, PasswordForm::Layout layout);
 std::ostream& operator<<(std::ostream& os,
                          const autofill::PasswordForm& form);
 
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_COMMON_PASSWORD_FORM_H__