Fix the flaky KioskAppManageTest::RemoveApp and UpdateAndRemove tests flaky issue caused by file de…

chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc

Index: chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc
diff --git a/chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc b/chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc
index 1bd54e43ff045a95c1ca971e1a0bb78c6da89e5d..ac5720ef75c212cdd8f74f21e22783d7d5e81650 100644
--- a/chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc
+++ b/chrome/browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc
@@ -551,7 +551,7 @@ IN_PROC_BROWSER_TEST_F(KioskAppManagerTest, RemoveApp) {
 
   // Remove the app now.
   manager()->RemoveApp(kTestLocalFsKioskApp);
-  content::RunAllPendingInMessageLoop(BrowserThread::FILE);
+  content::BrowserThread::GetBlockingPool()->FlushForTesting();
   manager()->GetApps(&apps);
   ASSERT_EQ(0u, apps.size());
   EXPECT_FALSE(base::PathExists(crx_path));
@@ -633,7 +633,7 @@ IN_PROC_BROWSER_TEST_F(KioskAppManagerTest, UpdateAndRemoveApp) {
 
   // Remove the app now.
   manager()->RemoveApp(kTestLocalFsKioskApp);
-  content::RunAllPendingInMessageLoop(BrowserThread::FILE);
+  content::BrowserThread::GetBlockingPool()->FlushForTesting();
   manager()->GetApps(&apps);
   ASSERT_EQ(0u, apps.size());
   // Verify both v1 and v2 crx files are removed.