Add delay to didAssociateFormControlsTimer so it doesn't fire too frequently

chrome/renderer/autofill/password_generation_agent_browsertest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <string.h>
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 485 matching lines @@
       "first_password.id = 'first_password';"
       "first_password.name = 'first_password';"
       "var second_password = document.createElement('input');"
       "second_password.type = 'password';"
       "second_password.id = 'second_password';"
       "second_password.name = 'second_password';"
       "form.appendChild(username);"
       "form.appendChild(first_password);"
       "form.appendChild(second_password);"
       "document.body.appendChild(form);");
-  ProcessPendingMessages();
+  WaitForAutofillDidAssociateFormControl();
 
   // This needs to come after the DOM has been modified.
   SetAccountCreationFormsDetectedMessage(password_generation_,
                                          GetMainFrame()->document(), 1, 1);
 
   // TODO(gcasto): I'm slightly worried about flakes in this test where
   // didAssociateFormControls() isn't called. If this turns out to be a problem
   // adding a call to OnDynamicFormsSeen(GetMainFrame()) will fix it, though
   // it will weaken the test.
   ExpectGenerationAvailable("first_password", true);
@@ skipping 168 matching lines @@
                                    base::string16());
 }
 
 TEST_F(PasswordGenerationAgentTest, FormClassifierDisabled) {
   LoadHTMLWithUserGesture(kSigninFormHTML);
   ExpectFormClassifierVoteReceived(false /* vote is not expected */,
                                    base::string16());
 }
 
 }  // namespace autofill