Check the return value of Platform::current()->currentThread() for media_blink_unittests.

Source/platform/Timer.cpp

Index: Source/platform/Timer.cpp
diff --git a/Source/platform/Timer.cpp b/Source/platform/Timer.cpp
index 33f33481e0e166583ae9c0817637767e09da58e0..25ac67ec8bee57bb9e7b888d0ab245a5999861bb 100644
--- a/Source/platform/Timer.cpp
+++ b/Source/platform/Timer.cpp
@@ -46,7 +46,7 @@ TimerBase::TimerBase()
     , m_unalignedNextFireTime(0)
     , m_repeatInterval(0)
     , m_cancellableTimerTask(nullptr)
-    , m_webScheduler(Platform::current()->currentThread()->scheduler())
+    , m_webScheduler(Platform::current()->currentThread() ? Platform::current()->currentThread()->scheduler() : nullptr)
 #if ENABLE(ASSERT)
     , m_thread(currentThread())
 #endif
@@ -104,7 +104,8 @@ void TimerBase::setNextFireTime(double now, double delay)
         if (m_cancellableTimerTask)
             m_cancellableTimerTask->cancel();
         m_cancellableTimerTask = new CancellableTimerTask(this);
-        m_webScheduler->postTimerTask(m_location, m_cancellableTimerTask, delayMs);
+        if (m_webScheduler)
+            m_webScheduler->postTimerTask(m_location, m_cancellableTimerTask, delayMs);
     }
 }