Switch AccessibilityMode to be a bitmap

content/public/browser/browser_accessibility_state.h

Index: content/public/browser/browser_accessibility_state.h
diff --git a/content/public/browser/browser_accessibility_state.h b/content/public/browser/browser_accessibility_state.h
index 6f8d6d2c8c1a8e3db4a69f4a4bb4b901dc895693..6c91e1b7b7699734675ebe734dba84c711e96fea 100644
--- a/content/public/browser/browser_accessibility_state.h
+++ b/content/public/browser/browser_accessibility_state.h
@@ -24,9 +24,15 @@ class CONTENT_EXPORT BrowserAccessibilityState {
   // Enables accessibility for all running tabs.
   virtual void EnableAccessibility() = 0;
 
-  // Disables accessibility for all running tabs.
+  // Disables accessibility for all running tabs. (Only if accessibility is not
+  // required by a command line flag or by a platform requirement.)
   virtual void DisableAccessibility() = 0;
 
+  // Resets accessibility to the platform default for all running tabs.
+  // This is probably off, but may be on, if --force_renderer_accessibility is
+  // passed, or EditableTextOnly if this is Win7.
+  virtual void ResetAccessibilityMode() = 0;
+
   // Called when screen reader client is detected.
   virtual void OnScreenReaderDetected() = 0;