Plumb Push API permission request through Blink using Frame.

public/platform/WebCallback.h

Index: public/platform/WebCallback.h
diff --git a/public/platform/WebCallback.h b/public/platform/WebCallback.h
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index 0000000000000000000000000000000000000000..0d23df3a535b2c48e2b9be011b84f6e279ec420f
--- /dev/null
+++ b/public/platform/WebCallback.h
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+// 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 WebCallback_h
+#define WebCallback_h
+
+namespace blink {
+
+class WebCallback {
+public:
+    virtual ~WebCallback() { };
+    virtual void run() { };
+};
+
+} // namespace blink
+
+#endif // WebCallback_h