text: // Copyright (c) 2011 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_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
  #define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
  #pragma once
  
  #include <string>
  #include <vector>
  
  #include "base/callback.h"
  #include "base/memory/singleton.h"
  #include "base/values.h"
  #include "chrome/browser/accessibility_events.h"
  #include "chrome/browser/extensions/extension_function.h"
  #include "content/common/notification_observer.h"
  #include "content/common/notification_registrar.h"
  
  // Observes the profile and routes accessibility notifications as events
  // to the extension system.
  class ExtensionAccessibilityEventRouter : public NotificationObserver {
   public:
    // Single instance of the event router.
    static ExtensionAccessibilityEventRouter* GetInstance();
  
    // Safe to call multiple times.
    void ObserveProfile(Profile* profile);
  
    // Get the dict representing the last control that received an
    // OnControlFocus event.
    DictionaryValue* last_focused_control_dict() {
      return &last_focused_control_dict_;
    }
  
    // Accessibility support is disabled until an extension expicitly enables
    // it, so that this extension api has no impact on Chrome's performance
    // otherwise.  These methods handle enabling, disabling, querying the
    // status, and installing callbacks to execute when accessibility support
    // is enabled or disabled.
    void SetAccessibilityEnabled(bool enabled);
    bool IsAccessibilityEnabled() const;
    typedef Callback0::Type Callback;
    void AddOnEnabledListener(Callback* callback);
    void AddOnDisabledListener(Callback* callback);
  
   private:
    friend struct DefaultSingletonTraits<ExtensionAccessibilityEventRouter>;
  
    ExtensionAccessibilityEventRouter();
    virtual ~ExtensionAccessibilityEventRouter();
  
    // NotificationObserver::Observe.
    virtual void Observe(NotificationType type,
                         const NotificationSource& source,
                         const NotificationDetails& details);
  
    void OnWindowOpened(const AccessibilityWindowInfo* details);
    void OnWindowClosed(const AccessibilityWindowInfo* details);
    void OnControlFocused(const AccessibilityControlInfo* details);
    void OnControlAction(const AccessibilityControlInfo* details);
    void OnTextChanged(const AccessibilityControlInfo* details);
    void OnMenuOpened(const AccessibilityMenuInfo* details);
    void OnMenuClosed(const AccessibilityMenuInfo* details);
  
    void DispatchEvent(Profile* profile,
                       const char* event_name,
                       const std::string& json_args);
  
    // Used for tracking registrations to history service notifications.
    NotificationRegistrar registrar_;
  
    DictionaryValue last_focused_control_dict_;
  
    bool enabled_;
    std::vector<Callback*> on_enabled_listeners_;
    std::vector<Callback*> on_disabled_listeners_;
  
    DISALLOW_COPY_AND_ASSIGN(ExtensionAccessibilityEventRouter);
  };
  
  // API function that enables or disables accessibility support.  Event
  // listeners are only installed when accessibility support is enabled, to
  // minimize the impact.
  class SetAccessibilityEnabledFunction : public SyncExtensionFunction {
    virtual ~SetAccessibilityEnabledFunction() {}
    virtual bool RunImpl();
    DECLARE_EXTENSION_FUNCTION_NAME(
        "experimental.accessibility.setAccessibilityEnabled")
  };
  
  // API function that returns the most recent focused control.
  class GetFocusedControlFunction : public SyncExtensionFunction {
    virtual ~GetFocusedControlFunction() {}
    virtual bool RunImpl();
    DECLARE_EXTENSION_FUNCTION_NAME(
        "experimental.accessibility.getFocusedControl")
  };
  
  #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
  