Cast: Added missing DCHECKs to ThreadChecker calls and minor cleanup.

media/cast/logging/simple_event_subscriber_unittest.cc

Index: media/cast/logging/simple_event_subscriber_unittest.cc
diff --git a/media/cast/logging/simple_event_subscriber_unittest.cc b/media/cast/logging/simple_event_subscriber_unittest.cc
index 5a6b09d054ff97b437c14a67450ecf3aa2072940..ab031266c2f154d49fab1c73780876dda70de3f1 100644
--- a/media/cast/logging/simple_event_subscriber_unittest.cc
+++ b/media/cast/logging/simple_event_subscriber_unittest.cc
@@ -23,8 +23,7 @@ class SimpleEventSubscriberTest : public ::testing::Test {
         cast_environment_(new CastEnvironment(
             scoped_ptr<base::TickClock>(testing_clock_).Pass(), task_runner_,
             task_runner_, task_runner_, task_runner_, task_runner_,
-            task_runner_, GetLoggingConfigWithRawEventsAndStatsEnabled())),
-        event_subscriber_(task_runner_) {
+            task_runner_, GetLoggingConfigWithRawEventsAndStatsEnabled())) {
     cast_environment_->Logging()->AddRawEventSubscriber(&event_subscriber_);
   }