Initial implementation of Cronet Async API.

components/cronet/android/cronet_url_request_adapter.h

Index: components/cronet/android/cronet_url_request_adapter.h
diff --git a/components/cronet/android/cronet_url_request_adapter.h b/components/cronet/android/cronet_url_request_adapter.h
new file mode 100644
index 0000000000000000000000000000000000000000..f2cbb6c7a971ff821048751d8a2ce91d5d367112
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+++ b/components/cronet/android/cronet_url_request_adapter.h
@@ -0,0 +1,148 @@
+// 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_CRONET_ANDROID_CRONET_URL_REQUEST_ADAPTER_H_
+#define COMPONENTS_CRONET_ANDROID_CRONET_URL_REQUEST_ADAPTER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/location.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/request_priority.h"
+#include "net/http/http_request_headers.h"
+#include "net/url_request/url_request.h"
+#include "url/gurl.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace net {
+class GrowableIOBuffer;
+class HttpResponseHeaders;
+}  // namespace net
+
+namespace cronet {
+
+class CronetURLRequestContextAdapter;
+
+// An adapter from the JNI CronetUrlRequest object to the Chromium URLRequest.
+// Created and configured from random thread. Start is posted to network
+// thread and all callbacks into CronetURLRequestAdapterDelegate are done on
+// network thread. Each delegate callback is expected to initiate next step like
+// FollowDeferredRedirect, ReadData or Destroy from random thread, which post
+// to network thread.

[mmenke, 2014/11/07 15:19:09]

Last two sentences are now incorrect.

Maybe "All methods except those needed to set up a request must be called
exclusively on the network thread."

[mef, 2014/11/07 16:22:25]

Done.

+class CronetURLRequestAdapter : public net::URLRequest::Delegate {
+ public:
+  // The delegate which is called when the request adapter completes a step.
+  // Always called on network thread.
+  class CronetURLRequestAdapterDelegate {
+   public:
+    // Called on redirect. Embedder should either destroy the request, or
+    // call FollowDeferredRedirect.
+    virtual void OnRedirect(const GURL& newLocation, int http_status_code) = 0;
+    // Called when response has started and headers have been received. Embedder
+    // should either destroy the request, or call ReadData.
+    virtual void OnResponseStarted(int http_status_code) = 0;
+    // Called when response bytes were read. Embedder should consume data and
+    // either destroy the request, or call ReadData.

[mmenke, 2014/11/07 15:19:08]

Maybe add "The request may only be destroyed after the embedder is done with
|bytes_buffer (See rename suggestion)|, as deleting the request frees the
buffer."

[mef, 2014/11/07 16:22:25]

Done.

+    virtual void OnBytesRead(unsigned char* bytes_buffer,
+                             int bytes_read) = 0;
+    // Called when response has finished successfully. Embedder should destroy
+    // the request.
+    virtual void OnRequestFinished() = 0;
+    // Called when response has finished with error. Embedder should destroy
+    // the request.

[mmenke, 2014/11/07 15:19:09]

Instead of "embedder", should we use "consumer", or use passive voice?  It's not
the embedder that destroys the request on finish or error, but the cronet Java
code.  The adapter probably shouldn't even know what an embedder is.

[mef, 2014/11/07 16:22:25]

Done.

+    virtual void OnError(int net_error) = 0;
+
+    virtual ~CronetURLRequestAdapterDelegate() {}
+  };
+
+  CronetURLRequestAdapter(
+      CronetURLRequestContextAdapter* context,
+      scoped_ptr<CronetURLRequestAdapterDelegate> delegate,
+      const GURL& url,
+      net::RequestPriority priority);
+  ~CronetURLRequestAdapter() override;
+
+  // Methods called prior to Start are never called on network thread.
+
+  // Sets the request method GET, POST etc.
+  void set_method(const std::string& method) {
+    initial_method_ = method;
+  }
+
+  // Adds a header to the request before it starts.
+  void AddRequestHeader(const std::string& name, const std::string& value);
+
+  // Methods called only on network thread.
+
+  // Starts the request.
+  void Start();
+
+  // Follows redirect.
+  void FollowDeferredRedirect();
+
+  // Reads more data.
+  void ReadData();
+
+  // Releases all resources for the request and deletes the object itself.
+  void Destroy();
+
+  // When called during a OnRedirect or OnResponseStarted callback, these
+  // methods return the corresponding response information.
+
+  // Gets all response headers, as a HttpResponseHeaders object. Returns NULL
+  // if the last attempted request received no headers.
+  const net::HttpResponseHeaders* GetResponseHeaders() const;
+
+  // Gets NPN or ALPN Negotiated Protocol (if any) from HttpResponseInfo.
+  const std::string& GetNegotiatedProtocol() const;
+
+  // Returns true if response is coming from the cache.
+  bool GetWasCached() const;
+
+  // Gets the total amount of body data received from network after
+  // SSL/SPDY/QUIC decoding and proxy handling.  Basically the size of the body
+  // prior to decompression.
+  int64 GetTotalReceivedBytes() const;
+
+  // net::URLRequest::Delegate overrides.
+  void OnReceivedRedirect(net::URLRequest* request,
+                          const net::RedirectInfo& redirect_info,
+                          bool* defer_redirect) override;
+  void OnResponseStarted(net::URLRequest* request) override;
+  void OnReadCompleted(net::URLRequest* request, int bytes_read) override;
+
+  // Posts tasks to network thread.
+  bool PostTaskToNetworkThread(const tracked_objects::Location& from_here,
+                               const base::Closure& task);
+
+  // Returns true if currently running on network thread.

[mmenke, 2014/11/07 15:19:09]

nit:  Maybe "currently running" -> run / called / invoked.

[mef, 2014/11/07 16:22:26]

Done.

+  bool IsOnNetworkThread() const;

[mmenke, 2014/11/07 15:19:08]

Suggest moving these two methods up above the "Methods called only on network
thread." comment, as these may be called on any thread.

[mef, 2014/11/07 16:22:25]

Done.

+
+ private:
+  // Checks status of the request_adapter, return true if |is_success()| is
+  // true, otherwise report error and cancel request_adapter.
+  bool MaybeReportError(net::URLRequest* request) const;
+
+  CronetURLRequestContextAdapter* context_;
+  scoped_ptr<CronetURLRequestAdapterDelegate> delegate_;
+
+  const GURL initial_url_;
+  const net::RequestPriority initial_priority_;
+  std::string initial_method_;
+  net::HttpRequestHeaders initial_request_headers_;
+
+  scoped_refptr<net::IOBufferWithSize> read_buffer_;
+  scoped_ptr<net::URLRequest> url_request_;
+
+  DISALLOW_COPY_AND_ASSIGN(CronetURLRequestAdapter);
+};
+
+}  // namespace cronet
+
+#endif  // COMPONENTS_CRONET_ANDROID_CRONET_URL_REQUEST_ADAPTER_H_