Add a basic functionality to the force-saving menu item.

components/autofill/content/renderer/password_autofill_agent.cc

Index: components/autofill/content/renderer/password_autofill_agent.cc
diff --git a/components/autofill/content/renderer/password_autofill_agent.cc b/components/autofill/content/renderer/password_autofill_agent.cc
index eb2e06dbe78683c9c03c13020eb30d85bad58718..4f2ca86374ec4aa9e8769fba12fbb4666c9335de 100644
--- a/components/autofill/content/renderer/password_autofill_agent.cc
+++ b/components/autofill/content/renderer/password_autofill_agent.cc
@@ -967,6 +967,8 @@ bool PasswordAutofillAgent::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(AutofillMsg_SetLoggingState, OnSetLoggingState)
     IPC_MESSAGE_HANDLER(AutofillMsg_AutofillUsernameDataReceived,
                         OnAutofillUsernameDataReceived)
+    IPC_MESSAGE_HANDLER(AutofillMsg_FindFocusedPasswordForm,
+                        OnFindFocusedPasswordForm)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -1241,6 +1243,22 @@ void PasswordAutofillAgent::OnAutofillUsernameDataReceived(
   form_predictions_ = predictions;
 }
 
+void PasswordAutofillAgent::OnFindFocusedPasswordForm() {
+  blink::WebElement element = render_frame()->GetFocusedElement();
+
+  DCHECK(!element.isNull());

[Mike West, 2015/05/29 07:24:49]

Hrm. Execution doesn't stop while a context menu is open. It's entirely possible
for a site to pop up an ad, for instance, and move focus out from under you. It
seems like we should gracefully handle this case without crashing.

[msramek, 2015/05/29 11:57:21]

Ehh, thanks for the sanity check.

I also added a check whether input.form() exists, which I forgot about. Password
manager cannot handle form-less password fields, so it would make sense to also
change the logic in Blink not to show the button in that case.

An interesting side effect is that we might accidentally save a different
password if the focus changes to a different password field, but commands like
"Paste" seem to behave the same way.

The other comment explains why we return an empty form instead of just bailing.

+  DCHECK(element.hasHTMLTagName("input")) <<
+      base::UTF16ToASCII(element.tagName());
+
+  blink::WebInputElement input = element.to<blink::WebInputElement>();
+  DCHECK(input.isPasswordField());
+
+  scoped_ptr<PasswordForm> password_form(CreatePasswordForm(
+      input.form(), &nonscript_modified_values_, &form_predictions_));
+  Send(new AutofillHostMsg_FocusedPasswordFormFound(
+      routing_id(), *password_form));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // PasswordAutofillAgent, private: