Server push cancellation: add PushPromiseHelper which reflects information on the push promise.

net/spdy/push_delegate.h

+// Copyright (c) 2016 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 NET_SPDY_PUSH_DELEGATE_H_
+#define NET_SPDY_PUSH_DELEGATE_H_
+
+#include "net/base/net_export.h"
+#include "url/gurl.h"
+
+namespace net {
+
+// An interface to a class that reflects information on the pushed request.
+class NET_EXPORT PushPromiseHelper {

[Ryan Hamilton, 2016/10/28 00:32:22]

This class exists to be used by the delegate, right? If so, consider making it
an inner class of PushDelegate.

(Also one class is named "Push" and the other "PushPromise" that seems sub
optimal :> But while we're bikeshedding about names, you might consider
"ServerPush")

[Zhongyi Shi, 2016/11/07 22:07:03]

Done.

+ public:
+  virtual ~PushPromiseHelper() {}
+
+  // Cancels the push if it is not claimed yet.
+  virtual void Cancel() = 0;
+
+  // Gets the URL of the pushed request.
+  virtual const GURL& GetURL() = 0;
+};
+
+class NET_EXPORT PushDelegate {
+ public:
+  virtual ~PushDelegate() {}
+
+  // Invoked by session when a push promise has been received.
+  virtual void OnPush(std::unique_ptr<PushPromiseHelper> push_promise) = 0;

[Ryan Hamilton, 2016/10/28 00:32:22]

Instead of putting the URL into the Helper and then just passing in the helper,
I wonder if it would make more sense to pass in the URL as a distinct argument.

[Zhongyi Shi, 2016/11/07 22:07:03]

There would be only one implementation of PushDelegate and it should be used by
both Quic and Spdy. The reason we'd like to wrap up the URL with a Helper is to
make the interface same fore QUIC and Spdy while the Helper will be implemented
by both class which include a pointer to session(where the two implementations
differ).

[Ryan Hamilton, 2016/11/08 22:27:01]

But both places OnPush() is called, the URL is sitting right there and could
easily be passed into OnPush instead of sticking it into the Helper and then
having the Delegate call GetURL to get it out of the helper?

+};
+
+}  // namespace net
+
+#endif  // NET_SPDY_PUSH_DELEGATE_H_