Allow MojoAsyncResourceHandler::OnWillRead to complete asyncronously

content/browser/loader/mojo_async_resource_handler.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_BROWSER_LOADER_MOJO_ASYNC_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_MOJO_ASYNC_RESOURCE_HANDLER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 114 matching lines @@
                   mojom::URLLoaderClientPtr url_loader_client);
   void SendUploadProgress(const net::UploadProgress& progress);
   void OnUploadProgressACK();
 
   ResourceDispatcherHostImpl* rdh_;
   mojo::AssociatedBinding<mojom::URLLoader> binding_;
 
   bool has_checked_for_sufficient_resources_ = false;
   bool sent_received_response_message_ = false;
   bool is_using_io_buffer_not_from_writer_ = false;
+  // True if OnWillRead was deferred, in order to wait to be able to allocate a
+  // buffer.
+  bool did_defer_on_will_read_ = false;
   bool did_defer_on_writing_ = false;
   bool did_defer_on_redirect_ = false;
   base::TimeTicks response_started_ticks_;
   int64_t reported_total_received_bytes_ = 0;
 
+  // Pointer to parent's information about the read buffer. Only non-null while
+  // OnWillRead is deferred.
+  scoped_refptr<net::IOBuffer>* parent_buffer_ = nullptr;
+  int* parent_buffer_size_ = nullptr;
+
   mojo::SimpleWatcher handle_watcher_;
   std::unique_ptr<mojom::URLLoader> url_loader_;
   mojom::URLLoaderClientPtr url_loader_client_;
   scoped_refptr<net::IOBufferWithSize> buffer_;
   size_t buffer_offset_ = 0;
   size_t buffer_bytes_read_ = 0;
   scoped_refptr<SharedWriter> shared_writer_;
   mojo::ScopedDataPipeConsumerHandle response_body_consumer_handle_;
 
   std::unique_ptr<UploadProgressTracker> upload_progress_tracker_;
 
   base::WeakPtrFactory<MojoAsyncResourceHandler> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(MojoAsyncResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_MOJO_ASYNC_RESOURCE_HANDLER_H_