Add more fine-grained accessibility modes.

content/common/accessibility_mode_enums.h

 // Copyright 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_COMMON_ACCESSIBILITY_MODE_ENUMS_H_
 #define CONTENT_COMMON_ACCESSIBILITY_MODE_ENUMS_H_
 
 // Note: keep enums in content/browser/resources/accessibility/accessibility.js
 // in sync with these two enums.
 enum AccessibilityModeFlag {
-  // Accessibility updates are processed to create platform trees and events are
-  // passed to platform APIs in the browser.
-  AccessibilityModeFlagPlatform = 1 << 0,
+  // Native accessibility APIs, specific to each platform, are enabled.
+  // When this flag is set that indicates the presence of a third-party
+  // client accessing Chrome via accessibility APIs. However, unless one
+  // of the flags below is set, the contents of web pages will not be
+  // accessible.
+  ACCESSIBILITY_MODE_FLAG_NATIVE_APIS = 1 << 0,
 
-  // Accessibility is on, and the full tree is computed. If this flag is off,
-  // only limited information about editable text nodes is sent to the browser
-  // process. Useful for implementing limited UIA on tablets.
-  AccessibilityModeFlagFullTree = 1 << 1,
+  // The renderer process will generate an accessibility tree containing
+  // basic information about all nodes, including role, name, value,
+  // state, and location. This is the minimum flag required in order for
+  // web contents to be accessible, and the remaining flags are meaningless
+  // unless this one is set.
+  //
+  // Note that sometimes this flag will be set when
+  // ACCESSIBILITY_MODE_FLAG_NATIVE_APIS is not, when the content layer embedder
+  // is providing accessibility support via some other mechanism other than
+  // what's implemented in content/browser.
+  ACCESSIBILITY_MODE_FLAG_WEB_CONTENTS = 1 << 1,
+
+  // The accessibility tree will contain inline text boxes, which are
+  // necessary to expose information about line breaks and word boundaries.
+  // Without this flag, you can retrieve the plaintext value of a text field
+  // but not the information about how it's broken down into lines.
+  //
+  // Note that when this flag is off it's still possible to request inline
+  // text boxes for a specific node on-demand, asynchronously.
+  ACCESSIBILITY_MODE_FLAG_INLINE_TEXT_BOXES = 1 << 2,
+
+  // The accessibility tree will contain extra accessibility
+  // attributes typically only needed by screen readers and other
+  // assistive technology for blind users. Examples include text style
+  // attributes, table cell information, live region properties, range
+  // values, and relationship attributes.
+  ACCESSIBILITY_MODE_FLAG_SCREEN_READER = 1 << 3,
+
+  // The accessibility tree will contain the HTML tag name and HTML attributes
+  // for all accessibility nodes that come from web content.
+  ACCESSIBILITY_MODE_FLAG_HTML = 1 << 4,
 };
 
-enum AccessibilityMode {
-  // All accessibility is off.
-  AccessibilityModeOff = 0,
+typedef int AccessibilityMode;
 
-  // Renderer accessibility is on, and platform APIs are called.
-  AccessibilityModeComplete =
-      AccessibilityModeFlagPlatform | AccessibilityModeFlagFullTree,
+const AccessibilityMode AccessibilityModeOff = 0;
 
-  // Renderer accessibility is on, and events are passed to any extensions
-  // requesting automation, but not to platform accessibility.
-  AccessibilityModeTreeOnly = AccessibilityModeFlagFullTree,
-};
+const AccessibilityMode ACCESSIBILITY_MODE_COMPLETE =
+    ACCESSIBILITY_MODE_FLAG_NATIVE_APIS |
+    ACCESSIBILITY_MODE_FLAG_WEB_CONTENTS |
+    ACCESSIBILITY_MODE_FLAG_INLINE_TEXT_BOXES |
+    ACCESSIBILITY_MODE_FLAG_SCREEN_READER |
+    ACCESSIBILITY_MODE_FLAG_HTML;
+
+const AccessibilityMode ACCESSIBILITY_MODE_WEB_CONTENTS_ONLY =
+    ACCESSIBILITY_MODE_FLAG_WEB_CONTENTS |
+    ACCESSIBILITY_MODE_FLAG_INLINE_TEXT_BOXES |
+    ACCESSIBILITY_MODE_FLAG_SCREEN_READER |
+    ACCESSIBILITY_MODE_FLAG_HTML;
 
 #endif  // CONTENT_COMMON_ACCESSIBILITY_MODE_ENUMS_H_