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 5f3b03043eb0d6793db7fb47026ea428a26ab0ec..b017f9d48bc4acf5c296e0307e0a6b46cabef144 100644
--- a/components/autofill/content/renderer/autofill_agent.cc
+++ b/components/autofill/content/renderer/autofill_agent.cc
@@ -157,6 +157,7 @@ bool AutofillAgent::OnMessageReceived(const IPC::Message& message) {
                         OnAcceptDataListSuggestion)
     IPC_MESSAGE_HANDLER(AutofillMsg_AcceptPasswordAutofillSuggestion,
                         OnAcceptPasswordAutofillSuggestion)
+    IPC_MESSAGE_HANDLER(AutofillMsg_PreviewPassword, OnPreviewPassword)
     IPC_MESSAGE_HANDLER(AutofillMsg_RequestAutocompleteResult,
                         OnRequestAutocompleteResult)
     IPC_MESSAGE_UNHANDLED(handled = false)
@@ -436,10 +437,22 @@ void AutofillAgent::OnClearForm() {
 
 void AutofillAgent::OnClearPreviewedForm() {
   if (!element_.isNull()) {
-    if (password_autofill_agent_->DidClearAutofillSelection(element_))
+    if (password_autofill_agent_->DidClearAutofillSelection(element_) &&
+        !is_password_previewed_)
       return;
 
-    ClearPreviewedFormWithElement(element_, was_query_node_autofilled_);
+    if(is_password_previewed_) {
+      ClearPreviewedFormWithElement(
+          element_,
+          REQUIRE_NONE,
+          was_query_node_autofilled_,
+          password_autofill_agent_->WasPasswordAutofilled());
+    } else {
+      ClearPreviewedFormWithElement(element_,
+                                    REQUIRE_AUTOCOMPLETE,
+                                    was_query_node_autofilled_,
+                                    false);
+    }
   } else {
     // TODO(isherman): There seem to be rare cases where this code *is*
     // reachable: see [ http://crbug.com/96321#c6 ].  Ideally we would
@@ -473,6 +486,15 @@ void AutofillAgent::OnAcceptPasswordAutofillSuggestion(
   DCHECK(handled);
 }
 
+void AutofillAgent::OnPreviewPassword(const base::string16& username) {
+  was_query_node_autofilled_ = element_.isAutofilled();
+  bool handled = password_autofill_agent_->DidSelectAutofillSuggestion(
+      element_,
+      username);
+  is_password_previewed_ = handled;
+  DCHECK(handled);
+}
+
 void AutofillAgent::OnRequestAutocompleteResult(
     WebFormElement::AutocompleteResult result,
     const FormData& form_data) {