Updater: enable IntegrationTest.RegisterTestApp.

Flakiness is expected to be fixed by
https://chromium-review.googlesource.com/c/chromium/src/+/2441283

If not, revert this CL.

Bug: 1131654
Change-Id: Iecc0f750e62349a94df04309974147ab23f46f92
Fixed: 1131654
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2441380
Commit-Queue: Sorin Jianu <sorin@chromium.org>
Reviewed-by: Sorin Jianu <sorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813270}

chrome/updater/test/integration_tests.cc

@@ -59,8 +59,7 @@ TEST_F(IntegrationTest, InstallUninstall) {
 }
 
 #if defined(OS_MAC)
-// Flaky: https://crbug.com/1131654
-TEST_F(IntegrationTest, DISABLED_RegisterTestApp) {
+TEST_F(IntegrationTest, RegisterTestApp) {
   RegisterTestApp();
   ExpectInstalled();
   ExpectActiveVersion(UPDATER_VERSION_STRING);