Processing USERNAME reply from Autofill server in Password Manager

components/autofill/content/common/autofill_messages.h

Index: components/autofill/content/common/autofill_messages.h
diff --git a/components/autofill/content/common/autofill_messages.h b/components/autofill/content/common/autofill_messages.h
index 078ff83427e4180bbe7fb03dd7fcedfae5f70d44..8aca2622eef17728ef981472e6d026fae065a6af 100644
--- a/components/autofill/content/common/autofill_messages.h
+++ b/components/autofill/content/common/autofill_messages.h
@@ -102,6 +102,11 @@ IPC_ENUM_TRAITS_MAX_VALUE(
     blink::WebFormElement::AutocompleteResult,
     blink::WebFormElement::AutocompleteResultErrorInvalid)
 
+// IPC_MESSAGE macros fail on the std::map, when expanding. We need to define
+// a type to avoid that.
+using FormDataFieldDataMap =
+    std::map<autofill::FormData, autofill::FormFieldData>;
+
 // Autofill messages sent from the browser to the renderer.
 
 // Tells the render frame that a user gesture was observed somewhere in the tab
@@ -195,6 +200,12 @@ IPC_MESSAGE_ROUTED3(AutofillMsg_RequestAutocompleteResult,
 IPC_MESSAGE_ROUTED1(AutofillMsg_AccountCreationFormsDetected,
                     std::vector<autofill::FormData> /* forms */)
 
+// Sent when Autofill manager gets the query response from the Autofill server
+// which contains information about username fields for some forms.
+// |predictions| maps forms to their username fields.
+IPC_MESSAGE_ROUTED1(AutofillMsg_AutofillUsernameDataReceived,
+                    FormDataFieldDataMap /* predictions */)
+
 // Autofill messages sent from the renderer to the browser.
 
 // TODO(creis): check in the browser that the renderer actually has permission