Adds new experimental accessibility extension api to enable or disable native accessibility.

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 16cf706d3867dbd6980bd406224fa9fc4ddca612..6f8d6d2c8c1a8e3db4a69f4a4bb4b901dc895693 100644
--- a/content/public/browser/browser_accessibility_state.h
+++ b/content/public/browser/browser_accessibility_state.h
@@ -6,6 +6,7 @@
 #define CONTENT_PUBLIC_BROWSER_BROWSER_ACCESSIBILITY_STATE_H_
 
 #include "base/callback_forward.h"
+

[jam, 2013/05/02 22:34:06]

nit: no blank line

 #include "content/common/content_export.h"
 
 namespace content {
@@ -20,8 +21,11 @@ class CONTENT_EXPORT BrowserAccessibilityState {
   // Returns the singleton instance.
   static BrowserAccessibilityState* GetInstance();
 
-  // Called when accessibility is enabled manually (via command-line flag).
-  virtual void OnAccessibilityEnabledManually() = 0;
+  // Enables accessibility for all running tabs.

[jam, 2013/05/02 22:34:06]

nit: don't mention tabs in content, since that's a chrome concept. you can say
"WebContents" instead.

+  virtual void EnableAccessibility() = 0;
+
+  // Disables accessibility for all running tabs.
+  virtual void DisableAccessibility() = 0;
 
   // Called when screen reader client is detected.
   virtual void OnScreenReaderDetected() = 0;