[autofill] Add support for PSL domain matching for password autofill.

content/public/common/password_form.h

Index: content/public/common/password_form.h
diff --git a/content/public/common/password_form.h b/content/public/common/password_form.h
index 1a70685305b274874b49720e53a4f68c73aa6b28..b8ae8a16dd04e78e1629733f1a08326ffbae8574 100644
--- a/content/public/common/password_form.h
+++ b/content/public/common/password_form.h
@@ -54,6 +54,23 @@ struct CONTENT_EXPORT PasswordForm {
   // 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
+  // when two PasswordForms are matched when trying to find a login/pass pair
+  // for a site. It is only set to a non-empty value during a match of the
+  // original stored login/pass and the current observed form if all these
+  // statements are true:
+  // 1) The full signon_realm is not the same.
+  // 2) The registry controlled domain is the same. For example; foo.bar,
+  // m.foo.bar and www.foo.bar would all resolve to foo.bar if .bar is the
+  // public suffix.

[Ilya Sherman, 2013/06/19 09:40:54]

Optional nit: Would login.m.foo.bar also resolve to the same registry controlled
domain?  Might be nice to clarify here; or leave it omitted if you think that
would actually just make things more confusing / hard to follow.

[nyquist, 2013/06/19 22:56:06]

Done.

+  // 3) The scheme is the same.
+  // 4) The port is the same.
+  // For example, if you have a password for http://www.foo.bar (where .bar is

[Ilya Sherman, 2013/06/19 09:40:54]

nit: Prefer to avoid pronouns.  In this case, perhaps replace "you have a
password" to "Chrome has a saved password", "the login database has a saved
password", or something like that.

[nyquist, 2013/06/19 22:56:06]

Done.

+  // the public suffix) and the observed form is http://m.foo.bar,
+  // |original_signon_realm| must be set to http://www.foo.bar.
+  std::string original_signon_realm;
+
   // The URL (minus query parameters) containing the form. This is the primary
   // data used by the PasswordManager to decide (in longest matching prefix
   // fashion) whether or not a given PasswordForm result from the database is a