Add "previewing on hover" support for password field.

components/autofill/content/renderer/autofill_agent.cc

Index: components/autofill/content/renderer/autofill_agent.cc
diff --git a/components/autofill/content/renderer/autofill_agent.cc b/components/autofill/content/renderer/autofill_agent.cc
index ca8e10ef7a3bc1384eafd203d351c62ad3610f19..0d8f49a3050cf392522bbedb85c99308d1290f63 100644
--- a/components/autofill/content/renderer/autofill_agent.cc
+++ b/components/autofill/content/renderer/autofill_agent.cc
@@ -162,6 +162,8 @@ bool AutofillAgent::OnMessageReceived(const IPC::Message& message) {
                         OnAcceptDataListSuggestion)
     IPC_MESSAGE_HANDLER(AutofillMsg_AcceptPasswordAutofillSuggestion,
                         OnAcceptPasswordAutofillSuggestion)
+    IPC_MESSAGE_HANDLER(AutofillMsg_PreviewPasswordAutofillSuggestion,
+                        OnPreviewPasswordAutofillSuggestion)
     IPC_MESSAGE_HANDLER(AutofillMsg_RequestAutocompleteResult,
                         OnRequestAutocompleteResult)
     IPC_MESSAGE_UNHANDLED(handled = false)
@@ -486,7 +488,10 @@ void AutofillAgent::OnClearPreviewedForm() {
     if (password_autofill_agent_->DidClearAutofillSelection(element_))
       return;
 
-    ClearPreviewedFormWithElement(element_, was_query_node_autofilled_);
+    ClearPreviewedFormWithElement(
+        element_,
+        was_query_node_autofilled_,
+        password_autofill_agent_->WasPasswordAutofilled());

[Ilya Sherman, 2014/05/13 00:44:05]

This call site should not need to change as a result of the password changes. 
Those changes should be internal to the PasswordAutofillAgent class.

[ziran.sun, 2014/05/14 15:35:12]

Done.

   } else {
     // TODO(isherman): There seem to be rare cases where this code *is*
     // reachable: see [ http://crbug.com/96321#c6 ].  Ideally we would
@@ -523,6 +528,17 @@ void AutofillAgent::OnAcceptPasswordAutofillSuggestion(
   DCHECK(handled);
 }
 
+void AutofillAgent::OnPreviewPasswordAutofillSuggestion(
+    const base::string16& username,
+    const base::string16& password) {
+  was_query_node_autofilled_ = element_.isAutofilled();

[Ilya Sherman, 2014/05/13 00:44:05]

This should be tracked internally to the PasswordAutofillAgent class.  So,
you'll need two new instance variables within that class:
was_username_autofilled_ and was_password_autofilled_.

[ziran.sun, 2014/05/14 15:35:12]

Done.

+  bool handled = password_autofill_agent_->SelectSuggestion(
+      element_,
+      username,
+      password);
+  DCHECK(handled);
+}
+
 void AutofillAgent::OnRequestAutocompleteResult(
     WebFormElement::AutocompleteResult result,
     const base::string16& message,