Switch AccessibilityMode to be a bitmap

content/browser/accessibility/accessibility_mode_helper.h

Index: content/browser/accessibility/accessibility_mode_helper.h
diff --git a/content/browser/accessibility/accessibility_mode_helper.h b/content/browser/accessibility/accessibility_mode_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..7bad7e685a94a4de11f812338a9d1cdb4a2745ee
--- /dev/null
+++ b/content/browser/accessibility/accessibility_mode_helper.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_MODE_HELPER_H_
+#define CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_MODE_HELPER_H_
+
+#include "content/common/content_export.h"
+#include "content/common/view_message_enums.h"
+
+namespace content {
+
+// Adds the given accessibility mode constant to the given accessibility mode
+// bitmap.
+CONTENT_EXPORT AccessibilityMode
+    AddAccessibilityModeTo(AccessibilityMode to, AccessibilityMode mode_to_add);
+
+// Removes the given accessibility mode constant from the given 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.
+CONTENT_EXPORT AccessibilityMode
+    RemoveAccessibilityModeFrom(AccessibilityMode to,
+                                AccessibilityMode mode_to_remove);
+
+} //  namespace content
+
+#endif  // CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_MODE_HELPER_H_