Load CMA backend from shared library

chromecast/media/cma/backend/media_clock_device_default.h

Index: chromecast/media/cma/backend/media_clock_device_default.h
diff --git a/chromecast/media/cma/backend/media_clock_device_default.h b/chromecast/media/cma/backend/media_clock_device_default.h
index 1ac43875210764da80a7fc9e4fa3cb53a3951c61..827effced6388f38d59733b6be0617f96789596c 100644
--- a/chromecast/media/cma/backend/media_clock_device_default.h
+++ b/chromecast/media/cma/backend/media_clock_device_default.h
@@ -6,7 +6,9 @@
 #define CHROMECAST_MEDIA_CMA_BACKEND_MEDIA_CLOCK_DEVICE_DEFAULT_H_
 
 #include "base/macros.h"
-#include "chromecast/media/cma/backend/media_clock_device.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "chromecast/public/media/media_clock_device.h"
 
 namespace chromecast {
 namespace media {
@@ -19,19 +21,21 @@ class MediaClockDeviceDefault : public MediaClockDevice {
   // MediaClockDevice implementation.
   State GetState() const override;
   bool SetState(State new_state) override;
-  bool ResetTimeline(base::TimeDelta time) override;
+  bool ResetTimeline(TimeDelta time) override;
   bool SetRate(float rate) override;
-  base::TimeDelta GetTime() override;
+  TimeDelta GetTime() override;
 
  private:
   State state_;
 
   // Media time sampled at STC time |stc_|.
-  base::TimeDelta media_time_;
+  TimeDelta media_time_;
   base::TimeTicks stc_;
 
   float rate_;
 
+  base::ThreadChecker thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaClockDeviceDefault);
 };