Add IDL and initial Blink API for Background Sync

Source/modules/background_sync/SyncError.h

Index: Source/modules/background_sync/SyncError.h
diff --git a/Source/modules/push_messaging/PushError.h b/Source/modules/background_sync/SyncError.h
similarity index 48%
copy from Source/modules/push_messaging/PushError.h
copy to Source/modules/background_sync/SyncError.h
index d7f87c3d5d4add04ad63f1aab2b53da0f1ceb027..0e9e036221d2bcbb41f1ae71c1622683c7f26e00 100644
--- a/Source/modules/push_messaging/PushError.h
+++ b/Source/modules/background_sync/SyncError.h
@@ -1,30 +1,30 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
+// Copyright 2015 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 PushError_h
-#define PushError_h
+#ifndef SyncError_h
+#define SyncError_h
 
 #include "core/dom/DOMException.h"
 #include "platform/heap/Handle.h"
-#include "public/platform/modules/push_messaging/WebPushError.h"
+#include "public/platform/modules/background_sync/WebSyncError.h"
 
 namespace blink {
 
 class ScriptPromiseResolver;
 
-class PushError {
-    WTF_MAKE_NONCOPYABLE(PushError);
+class SyncError {
+    WTF_MAKE_NONCOPYABLE(SyncError);
 public:
     // For CallbackPromiseAdapter.
-    typedef WebPushError WebType;
-    static PassRefPtrWillBeRawPtr<DOMException> take(ScriptPromiseResolver*, WebType* webErrorRaw);
-    static void dispose(WebType* webErrorRaw);
+    using WebType = WebSyncError;
+    static PassRefPtrWillBeRawPtr<DOMException> take(ScriptPromiseResolver*, WebType*);
+    static void dispose(WebType*);
 
 private:
-    PushError() = delete;
+    SyncError() = delete;
 };
 
 } // namespace blink
 
-#endif // PushError_h
+#endif // SyncError_h