Adding the Copresence RpcHandler and HttpPost helper.

components/copresence/rpc/http_post.h

+// 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 COMPONENTS_COPRESENCE_RPC_HTTP_POST_H_
+#define COMPONENTS_COPRESENCE_RPC_HTTP_POST_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/url_request/url_fetcher_delegate.h"
+
+namespace google {
+namespace protobuf {
+class MessageLite;
+}
+}
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace copresence {
+
+// This class handles all Apiary calls to the Copresence server.
+// It configures the HTTP request appropriately and reports any errors.
+// If deleted, the HTTP request is cancelled.
+//
+// TODO(ckehoe): Add retry logic.
+class HttpPost : public net::URLFetcherDelegate {
+ public:
+  // Callback to receive the HTTP status code and body of the response
+  // (if any). A pointer to this HttpPost object is also passed along.
+  typedef base::Callback<void(int, const std::string&, HttpPost*)>
+      ResponseCallback;
+
+  // An id for testing url fetching.
+  static const int kUrlFetcherId = 1;
+
+  // Send a request to the Copresence server. After calling the callback, this
+  // object will delete itself. |url_context_getter| is owned by the caller,
+  // and the context it provides must be available until the request completes.
+  // If this context is being destructed, call Cancel().
+  HttpPost(net::URLRequestContextGetter* url_context_getter,
+           const std::string& server_host,
+           const std::string& rpc_name,
+           const google::protobuf::MessageLite& request_proto,
+           const ResponseCallback& response_callback);

[willchan no longer on Chromium, 2014/08/08 01:05:59]

This response callback doesn't make sense to me. It's redundant. This sounds
like.

Mom: Son, I'm dropping you off at school. Here's a cell phone so you can text me
to let me know when to pick you up. Remember to mention who you are in the text
message.
Son: Why do I have to do that mom? You're the one giving me this cell phone and
it has a unique phone number. Why do I have to say who I am?
Mom: Because I said so.

Mom is the owner of the HttpPost. The HttpPost is the Son. It doesn't make sense
that the ResponseCallback (the cell phone) needs to take the HttpPost* as a
parameter. The HttpPost owner is creating the HttpPost::ResponseCallback. Create
a callback that is already bound to the appropriate HttpPost*.

[Charlie, 2014/08/08 21:57:53]

Good idea. Fixed.

Though I would have gotten it faster without the story :-)

[Charlie, 2014/08/08 22:25:47]

Turns out I did this one wrong after all. Stay tuned for a real fix.

+
+  // HTTP requests are cancelled on delete.
+  virtual ~HttpPost();
+
+ private:
+  // Overridden from net::URLFetcherDelegate.
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
+
+  ResponseCallback response_callback_;
+  scoped_ptr<net::URLFetcher> url_fetcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(HttpPost);
+};
+
+}  // namespace copresence
+
+#endif  // COMPONENTS_COPRESENCE_RPC_HTTP_POST_H_