Move some accessibility methods, enums and interfaces into the content/public API.

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..1d0955064975bfcd2ff0e9c85eb7edf5b56b1bba 100644
--- a/content/public/browser/browser_accessibility_state.h
+++ b/content/public/browser/browser_accessibility_state.h
@@ -7,6 +7,7 @@
 
 #include "base/callback_forward.h"
 #include "content/common/content_export.h"
+#include "content/public/common/accessibility_mode.h"
 
 namespace content {
 
@@ -29,6 +30,9 @@ class CONTENT_EXPORT BrowserAccessibilityState {
   // Returns true if the browser should be customized for accessibility.
   virtual bool IsAccessibleBrowser() = 0;
 
+  virtual AccessibilityMode GetAccessibilityMode() = 0;
+  virtual void SetAccessibilityMode(AccessibilityMode mode) = 0;
+
   // Add a callback method that will be called once, a small while after the
   // browser starts up, when accessibility state histograms are updated.
   // Use this to register a method to update additional accessibility