Move Push-related Blink API headers into their own directory.

public/platform/WebPushError.h

Index: public/platform/WebPushError.h
diff --git a/public/platform/WebPushError.h b/public/platform/WebPushError.h
index 56a89791efc48b41fdda986392cbb5421ed9e988..09cd2ae120c8d7b693df11d618c2c3cf1238ae37 100644
--- a/public/platform/WebPushError.h
+++ b/public/platform/WebPushError.h
@@ -1,33 +1 @@
-// 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 WebPushError_h
-#define WebPushError_h
-
-#include "WebString.h"
-
-namespace blink {
-
-struct WebPushError {
-    enum ErrorType {
-        ErrorTypeAbort = 0,
-        ErrorTypeNetwork,
-        ErrorTypeNotFound,
-        ErrorTypeUnknown,
-        ErrorTypeLast = ErrorTypeUnknown
-    };
-
-    WebPushError(ErrorType errorType, const WebString& message)
-        : errorType(errorType)
-        , message(message)
-    {
-    }
-
-    ErrorType errorType;
-    WebString message;
-};
-
-} // namespace blink
-
-#endif // WebPushError_h
+#include "public/platform/modules/push_messaging/WebPushError.h"