[Password Autofill] Make better use of prefilled usernames.

components/autofill/content/renderer/password_autofill_agent.h

Index: components/autofill/content/renderer/password_autofill_agent.h
diff --git a/components/autofill/content/renderer/password_autofill_agent.h b/components/autofill/content/renderer/password_autofill_agent.h
index a389ed2fae6e892fa67b794943690132c647bdaf..131d3a951c5aa82831afd9a1c5a8ad10ebf56d91 100644
--- a/components/autofill/content/renderer/password_autofill_agent.h
+++ b/components/autofill/content/renderer/password_autofill_agent.h
@@ -107,6 +107,15 @@ class PasswordAutofillAgent : public content::RenderViewObserver {
   bool ShowSuggestionPopup(const PasswordFormFillData& fill_data,
                            const WebKit::WebInputElement& user_input);
 
+  // When passwords are first recieved, see if we can autofill. This will try to
+  // autofill with the preferred username, but if the username field has a
+  // prefilled value we will try and fill the password for that username

[Ilya Sherman, 2013/11/04 23:10:48]

nit: "try and" -> "try to", or just "fill", depending on whether the filling is
certain or not.

[Garrett Casto, 2013/11/05 00:40:35]

Done.

+  // instead.

[Ilya Sherman, 2013/11/04 23:10:48]

nit: Please try to rewrite this comment without using the pronoun "we", which is
discouraged as the referent can be hard to infer.

[Garrett Casto, 2013/11/05 00:40:35]

Done.

[Ilya Sherman, 2013/11/05 01:25:11]

Hmm, I think the phrasing is still a little confusing.  How about something like
the following?

"""Attempts to fill |username_element| and |password_element| with the
|fill_data|.  Will use the data corresponding to the preferred username, unless
the |username_element| already has a value set.  In that case, attempts to fill
the password matching the already filled username, if such a password exists."""

Incidentally, I'm not really sure why we're passing the |form_element|
separately into this method -- shouldn't it be deducible from the
username_element and password_element params?  Can we drop it entirely?

[Garrett Casto, 2013/11/05 01:56:39]

Updated comment, and deduced form_element from username_element.

+  void FillFormOnPasswordRecieved(const PasswordFormFillData& fill_data,
+                                  const WebKit::WebFormElement& form_element,
+                                  WebKit::WebInputElement username_element,
+                                  WebKit::WebInputElement password_element);
+
   bool FillUserNameAndPassword(
       WebKit::WebInputElement* username_element,
       WebKit::WebInputElement* password_element,