Disable some AliveCheckerTests, which are inherently flaky.

Bug: 789804
Change-Id: I58f9b55c85efd1e3dc6cca47798aa6e3b2aad1b7
Reviewed-on: https://chromium-review.googlesource.com/822732Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523624}

media/audio/alive_checker_unittest.cc

@@ -218,7 +218,9 @@ class AliveCheckerTest : public testing::Test {
 };
 
 // Start and Stop the checker, verify that we get no dead detection.
-TEST_F(AliveCheckerTest, StartStop) {
+// TODO(crbug.com/789804): Fix the test not to be flaky, e.g. by switching to
+// using a mocked clock, and re-enable it.
+TEST_F(AliveCheckerTest, DISABLED_StartStop) {
   CreateAliveChecker(false, false);
 
   StartAliveChecker();
@@ -263,7 +265,9 @@ TEST_F(AliveCheckerTest, NoAliveNotificationsDetectTwice) {
 
 // Start the checker, notify that the client is alive several times, then stop
 // the checker. Verify that it doesn't detect dead.
-TEST_F(AliveCheckerTest, NotifyThenStop) {
+// TODO(crbug.com/789804): Fix the test not to be flaky, e.g. by switching to
+// using a mocked clock, and re-enable it.
+TEST_F(AliveCheckerTest, DISABLED_NotifyThenStop) {
   CreateAliveChecker(false, false);
 
   StartAliveChecker();