Delete dead Device Motion code in Blink.

Source/core/loader/EmptyClients.h

Index: Source/core/loader/EmptyClients.h
diff --git a/Source/core/loader/EmptyClients.h b/Source/core/loader/EmptyClients.h
index cb093e5e5fa235d19bf6dedf6daa9ee4156cae9c..221ee03749ed96ae21c40b5cd8cfa1e26959db50 100644
--- a/Source/core/loader/EmptyClients.h
+++ b/Source/core/loader/EmptyClients.h
@@ -43,7 +43,6 @@
 #include "core/platform/graphics/FloatRect.h"
 #include "core/platform/network/ResourceError.h"
 #include "core/platform/text/TextCheckerClient.h"
-#include "modules/device_orientation/DeviceMotionClient.h"
 #include "public/platform/WebScreenInfo.h"
 #include "wtf/Forward.h"
 
@@ -373,13 +372,6 @@ public:
     virtual void stopUpdating() OVERRIDE { }
 };
 
-class EmptyDeviceMotionClient : public DeviceMotionClient {
-public:
-    virtual void setController(DeviceMotionController*) OVERRIDE { }
-    virtual DeviceMotionData* lastMotion() const OVERRIDE { return 0; }
-    virtual void deviceMotionControllerDestroyed() OVERRIDE { }
-};
-
 class EmptyDeviceOrientationClient : public DeviceOrientationClient {
 public:
     virtual void setController(DeviceOrientationController*) OVERRIDE { }