Implement DeviceLight

public/platform/WebDeviceLightListener.h

Index: public/platform/WebDeviceLightListener.h
diff --git a/public/platform/WebDeviceLightListener.h b/public/platform/WebDeviceLightListener.h
new file mode 100644
index 0000000000000000000000000000000000000000..4b40842c89800358956b3491b2488b42a31c0e3f
--- /dev/null
+++ b/public/platform/WebDeviceLightListener.h
@@ -0,0 +1,20 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WebDeviceLightListener_h
+#define WebDeviceLightListener_h
+
+namespace blink {
+
+class WebDeviceLightListener {
+public:
+    // This method is called every time new device light data is available.
+    virtual void didChangeDeviceLight(double) = 0;
+
+    virtual ~WebDeviceLightListener() { }
+};
+
+} // namespace blink
+
+#endif // WebDeviceLightListener_h