Increase HeartbeatManagerTest.UpdateTimerAfterStart test max time check to

make it less flaky on memory.fyi bots.

BUG=441291
R=chirantan@chromium.org

Review URL: https://codereview.chromium.org/794303002

Cr-Commit-Position: refs/heads/master@{#308434}

google_apis/gcm/engine/heartbeat_manager_unittest.cc

@@ -190,7 +190,7 @@ TEST_F(HeartbeatManagerTest, UpdateTimerAfterStart) {
   manager()->UpdateHeartbeatTimer(
       make_scoped_ptr(new base::Timer(true, false)));
   EXPECT_LT(manager()->GetNextHeartbeatTime() - heartbeat,
-            base::TimeDelta::FromMilliseconds(1));
+            base::TimeDelta::FromMilliseconds(5));
 }
 
 // Stopping the manager should reset the heartbeat timer.