Don't defer quitting in ExecuteScript and other helpers that use DOMMessageQueue.

chrome/browser/chromeos/login/supervised/supervised_user_test_base.cc

Index: chrome/browser/chromeos/login/supervised/supervised_user_test_base.cc
diff --git a/chrome/browser/chromeos/login/supervised/supervised_user_test_base.cc b/chrome/browser/chromeos/login/supervised/supervised_user_test_base.cc
index 8f6b79e78c65d7e4124f0d9def4debfbde940fc7..7cf4c415fa690731c4235f89454e25f225e7eec4 100644
--- a/chrome/browser/chromeos/login/supervised/supervised_user_test_base.cc
+++ b/chrome/browser/chromeos/login/supervised/supervised_user_test_base.cc
@@ -335,16 +335,24 @@ void SupervisedUserTestBase::FillNewUserData(const std::string& display_name) {
 void SupervisedUserTestBase::StartUserCreation(
     const std::string& button_id,
     const std::string& expected_display_name) {
+  base::RunLoop mount_wait_loop;
+  base::RunLoop add_key_wait_loop;

[achuithb, 2016/11/30 22:39:52]

ditto

[Alexander Semashko, 2016/12/01 12:24:59]

Done.

+  mock_homedir_methods_->set_mount_callback(mount_wait_loop.QuitClosure());
+  mock_homedir_methods_->set_add_key_callback(add_key_wait_loop.QuitClosure());
   EXPECT_CALL(*mock_homedir_methods_, MountEx(_, _, _, _)).Times(1);
   EXPECT_CALL(*mock_homedir_methods_, AddKeyEx(_, _, _, _, _)).Times(1);
 
   JSEval(std::string("$('").append(button_id).append("').click()"));
 
+  mount_wait_loop.Run();
+  add_key_wait_loop.Run();
   ::testing::Mock::VerifyAndClearExpectations(mock_homedir_methods_);
+  mock_homedir_methods_->set_mount_callback(base::Closure());
+  mock_homedir_methods_->set_add_key_callback(base::Closure());
 
   EXPECT_TRUE(registration_utility_stub_->register_was_called());
-  EXPECT_EQ(registration_utility_stub_->display_name(),
-            base::UTF8ToUTF16(expected_display_name));
+  EXPECT_EQ(base::UTF8ToUTF16(expected_display_name),
+            registration_utility_stub_->display_name());
 
   registration_utility_stub_->RunSuccessCallback("token");
 
@@ -353,6 +361,9 @@ void SupervisedUserTestBase::StartUserCreation(
 
   JSExpect(StringPrintf("%s == 'created'", kCurrentPage));
   JSEvalOrExitBrowser("$('supervised-user-creation-gotit-button').click()");
+
+  // TODO(achuith): There should probably be a wait for a specific event.
+  content::RunAllPendingInMessageLoop();
 }
 
 void SupervisedUserTestBase::SigninAsSupervisedUser(