Upstream Android proxy config service.

net/proxy/proxy_config_service_android.h

+// Copyright (c) 2012 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 NET_PROXY_PROXY_CONFIG_SERVICE_ANDROID_H_
+#define NET_PROXY_PROXY_CONFIG_SERVICE_ANDROID_H_
+#pragma once
+
+#include <string>
+
+#include "base/android/jni_android.h"
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "net/base/net_export.h"
+#include "net/proxy/proxy_config_service.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace net {
+
+class ProxyConfig;
+
+class NET_EXPORT ProxyConfigServiceAndroid : public ProxyConfigService {
+ public:
+  class Delegate;
+
+  // Callback that returns the value of the property identified by the provided
+  // key. If it was not found, an empty string is returned. Note that this
+  // interface does not let you distinguish an empty property from a
+  // non-existing property. This callback is invoked on the JNI thread.
+  typedef base::Callback<std::string (const std::string& property)>
+      GetPropertyCallback;
+
+  ProxyConfigServiceAndroid(base::SingleThreadTaskRunner* network_task_runner,
+                            base::SingleThreadTaskRunner* jni_task_runner);
+
+  virtual ~ProxyConfigServiceAndroid();
+
+  // Register JNI bindings.
+  static bool Register(JNIEnv* env);
+
+  // ProxyConfigService:
+  // Called only on the network thread.
+  virtual void AddObserver(Observer* observer) OVERRIDE;
+  virtual void RemoveObserver(Observer* observer) OVERRIDE;
+  virtual ConfigAvailability GetLatestProxyConfig(ProxyConfig* config) OVERRIDE;
+
+  // Separate class whose instance is owned by the Delegate class implemented in
+  // the header. That lets us decouple ProxySettingsChanged() from
+  // ProxyConfigServiceAndroid lifecycle without exposing the Delegate here in
+  // the header.
+  class JNICallback {

[Ryan Sleevi, 2012/06/01 18:10:58]

nit: Rather than explain this from the perspective of justification, just
explain what it does.

nit: The approach you've taken with this, requiring it take a Delegate in ctor,
has forced you to expose an implementation detail (Delegate) as a public type
(line 29), even though no consumer can actually use either it or this class.

The better approach would be:

class JNIDelegate {
 public:
  virtual void ProxySettingsChanged(JNIEnv*, jobject) = 0;
};

And then have a concrete implementation in the .cc.

From the perspective of the JNI bindings (where this interface really lives, but
understandably can't due to the auto-generated nature), all you care about is
that this method exists - and any users of the PCSA do not have to be exposed to
the Delegate details (line 29).

finally, style-nit: typenames & member classes before methods ( conceptually
lumped under typedefs/enums under
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Declar...
)

[Philippe, 2012/06/04 10:02:37]

Done. Good point. I made the implementation class nested in the Delegate class
to avoid adding a 'friend class JNIDelegateImpl' below. Please let me know if
you want me instead to add this friend declaration below and make the
implementation class part of the anonymous namespace. 

+   public:
+    JNICallback(Delegate* delegate) : delegate_(delegate) {}
+
+    // Called from Java (on JNI thread) to signal that the proxy settings have
+    // changed.
+    void ProxySettingsChanged(JNIEnv*, jobject);
+
+   private:
+    Delegate* const delegate_;
+  };
+
+ private:
+  friend class ProxyConfigServiceAndroidTestBase;
+
+  // For tests.
+  ProxyConfigServiceAndroid(base::SingleThreadTaskRunner* network_task_runner,
+                            base::SingleThreadTaskRunner* jni_task_runner,
+                            GetPropertyCallback get_property_callback);
+
+  // For tests.
+  void ProxySettingsChanged();
+
+  scoped_refptr<Delegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProxyConfigServiceAndroid);
+};
+
+} // namespace net
+
+#endif // NET_PROXY_PROXY_CONFIG_SERVICE_ANDROID_H_