Add password manager autocomplete suggestion when a username element in clicked.

components/autofill/content/renderer/test_password_autofill_agent.cc

Index: components/autofill/content/renderer/test_password_autofill_agent.cc
diff --git a/components/autofill/content/renderer/test_password_autofill_agent.cc b/components/autofill/content/renderer/test_password_autofill_agent.cc
index af2a543a308d54f51044fd1f254368e0b1d37e50..e0355cf2e1ede0c37a579cf9e983c515eafc8828 100644
--- a/components/autofill/content/renderer/test_password_autofill_agent.cc
+++ b/components/autofill/content/renderer/test_password_autofill_agent.cc
@@ -8,7 +8,7 @@ namespace autofill {
 
 TestPasswordAutofillAgent::TestPasswordAutofillAgent(
     content::RenderView* render_view)
-    : PasswordAutofillAgent(render_view) {}
+    : PasswordAutofillAgent(render_view), pause_messages_(false) {}
 
 TestPasswordAutofillAgent::~TestPasswordAutofillAgent() {}
 
@@ -17,4 +17,18 @@ bool TestPasswordAutofillAgent::OriginCanAccessPasswordManager(
   return true;
 }
 
+bool TestPasswordAutofillAgent::Send(IPC::Message* message) {
+  if (pause_messages_) {
+    messages_.push_back(message);
+    return true;
+  }
+
+  return PasswordAutofillAgent::Send(message);
+}
+
+void TestPasswordAutofillAgent::resume_messages() {
+  pause_messages_ = false;
+  clear_messages();
+}
+
 }  // namespace autofill