Support transition between chrome and user mode console

chrome/browser/chromeos/dbus/console_service_provider.h

+// 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 CHROME_BROWSER_CHROMEOS_DBUS_CONSOLE_SERVICE_PROVIDER_H_
+#define CHROME_BROWSER_CHROMEOS_DBUS_CONSOLE_SERVICE_PROVIDER_H_
+
+#include "base/bind.h"
+#include "base/observer_list.h"
+#include "chrome/browser/chromeos/dbus/cros_dbus_service.h"
+#include "dbus/exported_object.h"
+#include "dbus/message.h"
+
+namespace dbus {
+class MethodCall;
+class Response;
+}
+
+namespace chromeos {
+
+// This class provides an api for external apps to notify
+// chrome that it should release control of the display server.
+// The main client is the console application.   This can
+// also be used by crouton to take over the display.
+class ConsoleServiceProvider
+    : public CrosDBusService::ServiceProviderInterface {
+ public:
+  class Observer {
+   public:
+    virtual void OnActivateConsole(int console_id) = 0;

[Daniel Erat, 2014/11/01 13:57:44]

do you really need this observer interface? can ActivateConsole() instead just
call DisplayConfigurator directly? if so, that seems like it'd be simpler.

+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  ConsoleServiceProvider();
+  virtual ~ConsoleServiceProvider();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+  bool HasObserver(Observer* observer);
+
+  void Start(scoped_refptr<dbus::ExportedObject> exported_object) override;
+
+ private:
+  // This method will get called when a external process sends the dbus

[Daniel Erat, 2014/11/01 13:57:44]

nit: s/sends/calls/

+  // method ConsoleServiceInterface.ActivateConsole.  The method receives

[Daniel Erat, 2014/11/01 13:57:44]

nit: remove "ConsoleServiceInterface." here since that is no longer the case

+  // a single integer parameter |console_id| which indicates the console id.

[Daniel Erat, 2014/11/01 13:57:44]

nit: remove redundant "which indicates the console id"

+  // Chrome  will take ownership of the display service when the console

[Daniel Erat, 2014/11/01 13:57:44]

nit: remove extra space between "Chrome" and "will"

+  // id is 0 or 1.  It will relinquish control when the console_id is 2 or more
+  // to allow other entities (such as the console) to take control of the
+  // display.

[Daniel Erat, 2014/11/01 13:57:44]

what's the point of taking an int here and treating 0 and 1 specially, instead
of just taking a bool? looking at the other change, it's unclear to me that this
id is used for anything else:

void DisplayConfigurator::OnActivateConsole(int console_id) {
  LOG(ERROR) << "DisplayConfigurator::ActivateConsole: " << console_id;
  if (console_id < 2) {
    SetDisplayMode(display_state());
  } else {
    RelinquishControl();
  }
}

+  void ActivateConsole(dbus::MethodCall* method_call,
+                       dbus::ExportedObject::ResponseSender response_sender);
+
+  // This method is called when a dbus method is exported.  If the export of the
+  // method is successful, |success| will be true.  It will be false
+  // otherwise.
+  void OnExported(const std::string& interface_name,
+                  const std::string& method_name,
+                  bool success);
+
+  base::WeakPtrFactory<ConsoleServiceProvider> weak_ptr_factory_;
+  ObserverList<Observer> observers_;
+  DISALLOW_COPY_AND_ASSIGN(ConsoleServiceProvider);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_DBUS_CONSOLE_SERVICE_PROVIDER_H_