Add JSON serializer to MediaDeviceInfo.

third_party/WebKit/Source/modules/mediastream/MediaDeviceInfo.cpp

Index: third_party/WebKit/Source/modules/mediastream/MediaDeviceInfo.cpp
diff --git a/third_party/WebKit/Source/modules/mediastream/MediaDeviceInfo.cpp b/third_party/WebKit/Source/modules/mediastream/MediaDeviceInfo.cpp
index e2ce78d28eea5614018bcd2d14d72c6c4d52b0e7..e13f974ff2cd4b75f0b0d1a6811193b086ca49ed 100644
--- a/third_party/WebKit/Source/modules/mediastream/MediaDeviceInfo.cpp
+++ b/third_party/WebKit/Source/modules/mediastream/MediaDeviceInfo.cpp
@@ -26,6 +26,9 @@
 #include "config.h"
 #include "modules/mediastream/MediaDeviceInfo.h"
 
+#include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/ScriptValue.h"
+#include "bindings/core/v8/V8ObjectBuilder.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
@@ -71,4 +74,14 @@ String MediaDeviceInfo::groupId() const
     return m_webMediaDeviceInfo.groupId();
 }
 
+ScriptValue MediaDeviceInfo::toJSONForBinding(ScriptState* scriptState)
+{
+    V8ObjectBuilder result(scriptState);
+    result.addString("deviceId", deviceId());
+    result.addString("kind", kind());
+    result.addString("label", label());
+    result.addString("groupId", groupId());
+    return result.scriptValue();
+}
+
 } // namespace blink