[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..d4b977693d38965f191f383b99cadaa878812ad1 100644
--- a/content/public/common/password_form.h
+++ b/content/public/common/password_form.h
@@ -54,6 +54,16 @@ struct CONTENT_EXPORT PasswordForm {
   // data from the database, so it must not be empty.
   std::string signon_realm;
 
+  // The "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
+  // to a non-empty value if this is not a perfect match for same origin
+  // matching and instead just a match using the public suffix. In that case,
+  // this must be set to where this PasswordForm data originated from.
+  // For example, if you have a password for http://www.foo.bar (where .bar is

[palmer, 2013/06/11 18:55:45]

Document here what our scheme-matching (HTTP vs. HTTPS) policy is, and why.

My strong desire is still to never autofill from HTTPS forms into HTTP. I'd like
to have that documented and tested.

[nyquist, 2013/06/11 23:54:43]

Done.

+  // the public suffix) and it shows up on 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