Adds extension APIs of events on changing volume.

chrome/browser/accessibility_events.h

Index: chrome/browser/accessibility_events.h
diff --git a/chrome/browser/accessibility_events.h b/chrome/browser/accessibility_events.h
index 5d7a012efbc774dbdd363e141181e7ffe8d23827..09bf24c379885f4a0d26edf59d0907053bbda0f0 100644
--- a/chrome/browser/accessibility_events.h
+++ b/chrome/browser/accessibility_events.h
@@ -255,6 +255,21 @@ class AccessibilityMenuInfo : public AccessibilityControlInfo {
   virtual const char* type() const;
 };
 
+// Accessibility information about a volume; this class is used by
+// onVolumeUp, onVolumeDown, and onVolumeMute event listeners.
+class AccessibilityVolumeInfo : public AccessibilityControlInfo {

[dmazzoni, 2011/08/24 14:49:02]

I think AccessibilityVolumeInfo shouldn't inherit from AccessibilityControlInfo,
because it's not a control and none of the other events (focus, etc.) apply to
it.

[yoshiki, 2011/08/29 09:16:16]

Done.

+ public:
+  AccessibilityVolumeInfo(Profile* profile, double volume, bool is_mute);

[dmazzoni, 2011/08/24 14:49:02]

Add a comment with the possible volume range, like 0 - 100.

is_mute should be is_muted, throughout.

[yoshiki, 2011/08/29 09:16:16]

Done.

+
+  virtual const char* type() const;
+
+  virtual void SerializeToDict(base::DictionaryValue* dict) const;
+
+ private:
+  double volume_;
+  bool is_mute_;
+};
+
 // Accessibility information about a menu item; this class is used by
 // onControlFocused event listeners.
 class AccessibilityMenuItemInfo : public AccessibilityControlInfo {