Use mojo for Chrome Loading, Part 1

content/child/url_response_body_consumer.h

+// Copyright 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 CONTENT_CHILD_URL_RESPONSE_BODY_CONSUMER_H_
+#define CONTENT_CHILD_URL_RESPONSE_BODY_CONSUMER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <utility>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "content/common/content_export.h"
+#include "content/common/url_loader.mojom.h"
+#include "mojo/message_pump/handle_watcher.h"
+#include "mojo/public/cpp/system/data_pipe.h"
+
+namespace content {
+
+class ResourceDispatcher;
+struct ResourceRequestCompletionStatus;
+
+// This class pulls data from a data pipe and dispatches it to the
+// ResourceDispatcher.

[kinuko, 2016/08/04 16:07:03]

nit: also comment that this is used when IPC mode is mojo

[yhirano, 2016/08/05 12:21:40]

Done.

+class CONTENT_EXPORT URLResponseBodyConsumer final
+    : public base::RefCounted<URLResponseBodyConsumer> {
+ public:
+  URLResponseBodyConsumer(int request_id,
+                          ResourceDispatcher* resource_dispatcher,
+                          mojo::ScopedDataPipeConsumerHandle handle);
+
+  // Sets the completion status. Dispatches the completion status to the
+  // ResourceDispatcher when the both following conditions hold:
+  //  1) The completion status is set by this function, and

[kinuko, 2016/08/04 16:07:03]

I wasn't quite sure what this comment actually means, does it mean 'it hasn't
been cancelled' (from what I saw in the code)?

[yhirano, 2016/08/05 12:21:40]

No. It means this class stores the completion notification until it sees the
end-of-body.

[kinuko, 2016/08/08 15:47:25]

I see, so it's not really about the behavior of this method but of this class. 
Then how about we slightly rephrase it to:

"The completion status is dispatched to the ResourceDispatcher... :
1) This function has been called and the completion status is set, and"

[yhirano, 2016/08/09 06:35:48]

Done.

+  //  2) All data is read from the handle.
+  void OnComplete(const ResourceRequestCompletionStatus& status);
+
+  // Cancels watching the handle and dispatches an error to the
+  // ResourceDispatcher. This function does nothing if the reading is already
+  // cancelled or done.
+  void Cancel();
+
+ private:
+  friend class base::RefCounted<URLResponseBodyConsumer>;
+  ~URLResponseBodyConsumer();
+
+  class ReceivedData;
+  void Reclaim(uint32_t size);
+
+  void OnReadable(MojoResult);
+  void StartWatching();
+  void NotifyCompletionIfAppropriate();
+
+  int request_id_;

[kinuko, 2016/08/04 16:07:03]

nit: const

[yhirano, 2016/08/05 12:21:40]

Done.

+  ResourceDispatcher* resource_dispatcher_;
+  mojo::ScopedDataPipeConsumerHandle handle_;
+  mojo::common::HandleWatcher handle_watcher_;
+  ResourceRequestCompletionStatus completion_status_;
+
+  bool has_received_completion_ = false;
+  bool has_been_cancelled_ = false;
+  bool has_seen_end_of_data_;
+
+  DISALLOW_COPY_AND_ASSIGN(URLResponseBodyConsumer);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_CHILD_URL_RESPONSE_BODY_CONSUMER_H_