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 "base/memory/weak_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.
+// Clients should not attempt to delete this class, as it needs to
+// persist until the HTTP request completes (or times out).
+//
+// TODO(ckehoe): Add retry logic.
+class HttpPost : public net::URLFetcherDelegate,
+                 public base::SupportsWeakPtr<HttpPost> {

[willchan no longer on Chromium, 2014/08/07 20:27:05]

Can you explain why this inherits from SupportsWeakPtr? That is generally
discouraged because we like to have explicit ownership. If someone else is
holding a WeakPtr<Foo>, it is more difficult to understand the lifetime of Foo.
If you need it internally for base::Bind(), I recommend using WeakPtrFactory
instead, since that don't expose WeakPtrs outside the class, which helps
consumers of this class understand the lifetime contract.

[Charlie, 2014/08/07 22:40:58]

You're right, WeakPtr isn't needed. It actually isn't used at all (anymore).

On 2014/08/07 20:27:05, willchan wrote:

+ 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,
+  // which will be deleted right after the callback completes.
+  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);
+
+  // Cancels the HTTP request and deletes this object. Call this
+  // if the URLRequestContext passed into the constructor is going away.
+  void Cancel();
+
+ private:
+  // This class deletes itself when the request completes (or times out).
+  // To delete it earlier, call Cancel().
+  virtual ~HttpPost();
+
+  // 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_