Add plumbing for platform based Device Motion testing.

webkit/support/webkit_support.cc

Index: webkit/support/webkit_support.cc
diff --git a/webkit/support/webkit_support.cc b/webkit/support/webkit_support.cc
index d1c8be35e99b786273c1b3e18176d8f00b3297f7..a9adb9121d84f574b04872ab8b43bac742fd22f0 100644
--- a/webkit/support/webkit_support.cc
+++ b/webkit/support/webkit_support.cc
@@ -695,4 +695,8 @@ void SetGamepadData(const WebKit::WebGamepads& pads) {
   test_environment->webkit_platform_support()->setGamepadData(pads);
 }
 
+void SetDeviceMotionData(const WebKit::WebDeviceMotionData& data) {
+  test_environment->webkit_platform_support()->setDeviceMotionData(data);
+}
+
 }  // namespace webkit_support