Initial implementation of Cronet Async API.

components/cronet/android/cronet_url_request_context_adapter.h

Index: components/cronet/android/cronet_url_request_context_adapter.h
diff --git a/components/cronet/android/cronet_url_request_context_adapter.h b/components/cronet/android/cronet_url_request_context_adapter.h
new file mode 100644
index 0000000000000000000000000000000000000000..48509499798de662cbc26a0faeb33a30d4722608
--- /dev/null
+++ b/components/cronet/android/cronet_url_request_context_adapter.h
@@ -0,0 +1,83 @@
+// 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_CONTEXT_ADAPTER_H_
+#define COMPONENTS_CRONET_ANDROID_CRONET_URL_REQUEST_CONTEXT_ADAPTER_H_
+
+#include <string>
+
+#include "base/compiler_specific.h"

[xunjieli, 2014/10/23 14:04:33]

Is this include being used?

[mef, 2014/10/24 03:31:44]

I think it used to define OVERRIDE, which is no longer needed.

+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread.h"
+#include "net/base/net_log.h"
+#include "net/base/network_change_notifier.h"
+#include "net/url_request/url_request_context_getter.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace net {
+class NetLogLogger;
+class URLRequestContext;
+}  // namespace net
+
+namespace cronet {
+
+struct URLRequestContextConfig;
+
+// Fully configured |URLRequestContext|.

[xunjieli, 2014/10/23 14:04:33]

nit: This comment does not make much sense to me. maybe consider rephrasing?

[mef, 2014/10/24 03:31:44]

Done.

+class CronetURLRequestContextAdapter : public net::URLRequestContextGetter {

[mmenke, 2014/10/23 16:26:01]

I don't think this works for cleanup - threads have to be destroyed on another
thread, but the request context and other network stuff needs to be deleted on
the network thread.

While we could make sure we destroy the refcounted context getter on a Java
thread, but the context on the network thread, the nature of being refcounted
makes that difficult to do.  So I think we should separate out the adapter and
the getter into separate classes - we may well not even not need the getter,
actually.

On destruction of the adapter (On a java thread), we then post a task to stop
the NetLogLogger and destroy the context on the network thread, and that's it -
destroying the thread will call Thread.Stop(), which will wait until all pending
tasks of the other thread have run, and we're done.

That does not take care of the issue of deleting the adapter while other
CronetUrlRequests are pending - we'll need more code for that.  Maybe a
Shutdown() function that throws an assertion if there are any pending
URLRequests (We'd have to keep a mutex-protected counter and a isShutdown
boolean in the context, Java-side, but I think that's not too bad).

[mef, 2014/10/24 19:57:55]

Done.

+ public:
+  class CronetURLRequestContextAdapterDelegate
+      : public base::RefCountedThreadSafe<
+            CronetURLRequestContextAdapterDelegate> {
+   public:
+    virtual void OnContextInitialized(
+        CronetURLRequestContextAdapter* context_adapter) = 0;
+
+   protected:
+    friend class base::RefCountedThreadSafe<
+        CronetURLRequestContextAdapterDelegate>;
+
+    virtual ~CronetURLRequestContextAdapterDelegate() {}
+  };
+
+  explicit CronetURLRequestContextAdapter(
+      CronetURLRequestContextAdapterDelegate* delegate);
+  void Initialize(scoped_ptr<URLRequestContextConfig> config);
+
+  const std::string& GetUserAgent(const GURL& url) const;

[mmenke, 2014/10/23 16:26:01]

Should get rid of this and just set it on the context builder.  It has all the
smarts to not override an explicitly set user agent on a request, so no need to
duplicate that logic.

[mef, 2014/10/24 03:31:44]

Done.

+
+  // net::URLRequestContextGetter implementation:
+  net::URLRequestContext* GetURLRequestContext() override;
+  scoped_refptr<base::SingleThreadTaskRunner> GetNetworkTaskRunner()
+      const override;
+
+  void StartNetLogToFile(const std::string& file_name);
+  void StopNetLog();
+
+ private:
+  scoped_refptr<CronetURLRequestContextAdapterDelegate> delegate_;
+  scoped_ptr<net::URLRequestContext> context_;
+  std::string user_agent_;
+  base::Thread* network_thread_;
+  scoped_ptr<net::NetworkChangeNotifier> network_change_notifier_;

[xunjieli, 2014/10/23 14:04:33]

nit: I don't think this is being used. Suggest also remove the header file from
includes.

[mef, 2014/10/24 03:31:44]

Done.

+  scoped_ptr<net::NetLogLogger> net_log_logger_;
+
+  virtual ~CronetURLRequestContextAdapter();
+
+  // Initializes |context_| on the Network thread.
+  void InitializeOnNetworkThread(scoped_ptr<URLRequestContextConfig> config);
+  void StartNetLogToFileOnNetworkThread(const std::string& file_name);
+  void StopNetLogOnNetworkThread();
+
+  DISALLOW_COPY_AND_ASSIGN(CronetURLRequestContextAdapter);
+};
+
+}  // namespace cronet
+
+#endif  // COMPONENTS_CRONET_ANDROID_CRONET_URL_REQUEST_CONTEXT_ADAPTER_H_