Remove dependency on NotificationService for cros a11y settings.

chrome/browser/chromeos/accessibility/accessibility_manager.h

Index: chrome/browser/chromeos/accessibility/accessibility_manager.h
diff --git a/chrome/browser/chromeos/accessibility/accessibility_manager.h b/chrome/browser/chromeos/accessibility/accessibility_manager.h
index f805ee5576c163a2cb24524d0cef70a7d16f95f3..41fb8bc40df0414afcf2a4e5190cd5dbea90104a 100644
--- a/chrome/browser/chromeos/accessibility/accessibility_manager.h
+++ b/chrome/browser/chromeos/accessibility/accessibility_manager.h
@@ -9,6 +9,7 @@
 
 #include "ash/accessibility_delegate.h"
 #include "ash/session_state_observer.h"
+#include "base/callback_list.h"
 #include "base/memory/weak_ptr.h"
 #include "base/prefs/pref_change_registrar.h"
 #include "base/time/time.h"
@@ -26,21 +27,42 @@ class Profile;
 
 namespace chromeos {
 
+enum AccessibilityNotificationType {
+  ACCESSIBILITY_MANAGER_SHUTDOWN,
+  ACCESSIBILITY_TOGGLE_HIGH_CONTRAST_MODE,
+  ACCESSIBILITY_TOGGLE_LARGE_CURSOR,
+  ACCESSIBILITY_TOGGLE_SCREEN_MAGNIFIER,
+  ACCESSIBILITY_TOGGLE_SPOKEN_FEEDBACK,
+  ACCESSIBILITY_TOGGLE_VIRTUAL_KEYBOARD
+};
+
 struct AccessibilityStatusEventDetails {
   AccessibilityStatusEventDetails(
+      AccessibilityNotificationType notification_type,
       bool enabled,
       ash::AccessibilityNotificationVisibility notify);
 
   AccessibilityStatusEventDetails(
+      AccessibilityNotificationType notification_type,
       bool enabled,
       ash::MagnifierType magnifier_type,
       ash::AccessibilityNotificationVisibility notify);
 
+  AccessibilityNotificationType notification_type;
   bool enabled;
   ash::MagnifierType magnifier_type;
   ash::AccessibilityNotificationVisibility notify;
 };
 
+typedef base::Callback<void(const AccessibilityStatusEventDetails&)>
+    AccessibilityStatusCallback;
+
+typedef base::CallbackList<void(const AccessibilityStatusEventDetails&)>
+    AccessibilityStatusCallbackList;
+
+typedef AccessibilityStatusCallbackList::Subscription
+    AccessibilityStatusSubscription;
+
 // AccessibilityManager changes the statuses of accessibility features
 // watching profile notifications and pref-changes.
 // TODO(yoshiki): merge MagnificationManager with AccessibilityManager.
@@ -144,6 +166,15 @@ class AccessibilityManager : public content::NotificationObserver,
   // Injects ChromeVox scripts into given |render_view_host|.
   void InjectChromeVox(content::RenderViewHost* render_view_host);
 
+  // Register a callback to be notified when the status of an accessibility
+  // option changes.
+  scoped_ptr<AccessibilityStatusSubscription> RegisterCallback(
+      const AccessibilityStatusCallback& cb);
+
+  // Notify registered callbacks of a status change in an accessibility setting.
+  void NotifyAccessibilityStatusChanged(
+      AccessibilityStatusEventDetails& details);
+
  protected:
   AccessibilityManager();
   virtual ~AccessibilityManager();
@@ -170,7 +201,6 @@ class AccessibilityManager : public content::NotificationObserver,
   void ReceiveBrailleDisplayState(
       scoped_ptr<extensions::api::braille_display_private::DisplayState> state);
 
-
   void SetProfile(Profile* profile);
 
   void UpdateChromeOSAccessibilityHistograms();
@@ -222,6 +252,8 @@ class AccessibilityManager : public content::NotificationObserver,
 
   bool system_sounds_enabled_;
 
+  AccessibilityStatusCallbackList callback_list_;

[David Tseng, 2014/02/21 17:42:59]

I'm unclear as to the ownership of this list. It's returned by RegisterCallback
and appears to be reset by external classes?

[kevers, 2014/02/21 17:52:31]

External classes reset/cancel their subscriptions when deleted. Subscribers are
also told when the accessibility manager is being shut down so that they can
release their subscriptions, which alleviates potential ordering problems on
shutdown.

[David Tseng, 2014/02/21 19:44:51]

Ok; thanks for clarifying.

+
   DISALLOW_COPY_AND_ASSIGN(AccessibilityManager);
 };