Switch AccessibilityMode to be a bitmap

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index df6dc8daa2bf9fa796b805eb4e3f1e51d2e9cc75..6cea67e0b8239f32a910bb0c55515ba943ff26fd 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -392,12 +392,18 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
       const std::vector<EditCommand>& commands);
 
   // Gets the accessibility mode.
-  AccessibilityMode accessibility_mode() const {
+  unsigned int accessibility_mode() const {
     return accessibility_mode_;
   }
 
-  // Send a message to the renderer process to change the accessibility mode.
-  void SetAccessibilityMode(AccessibilityMode mode);
+  // Adds the given accessibility mode to the current accessibility mode bitmap.
+  void AddAccessibilityMode(AccessibilityMode mode);
+
+  // Removes the given accessibility mode from the current accessibility mode
+  // bitmap, managing the bits that are shared with other modes such that a
+  // bit will only be turned off when all modes that depend on it have been
+  // removed.
+  void RemoveAccessibilityMode(AccessibilityMode mode);
 
   // Relay a request from assistive technology to perform the default action
   // on a given node.
@@ -758,6 +764,9 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
 
   void WindowSnapshotReachedScreen(int snapshot_id);
 
+  // Send a message to the renderer process to change the accessibility mode.
+  void SetAccessibilityMode(unsigned int AccessibilityMode);
+
   // Our delegate, which wants to know mainly about keyboard events.
   // It will remain non-NULL until DetachDelegate() is called.
   RenderWidgetHostDelegate* delegate_;
@@ -830,7 +839,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   gfx::Rect last_view_screen_rect_;
   gfx::Rect last_window_screen_rect_;
 
-  AccessibilityMode accessibility_mode_;
+  unsigned int accessibility_mode_;
 
   // Keyboard event listeners.
   std::vector<KeyPressEventCallback> key_press_event_callbacks_;