Set accessibility state for all frames. |accessibility_state| may be default, enabled or disabled. If |accessibility_state| is STATE_DEFAULT then accessibility will be disabled by default and the state may be further controlled with the "force-renderer-accessibility" and "disable- renderer-accessibility" command-line switches. If |accessibility_state| is STATE_ENABLED then accessibility will be enabled. If |accessibility_state| is STATE_DISABLED then accessibility will be completely disabled.

For windowed browsers accessibility will be enabled in Complete mode (which corresponds to kAccessibilityModeComplete in Chromium). In this mode all platform accessibility objects will be created and managed by Chromium's internal implementation. The client needs only to detect the screen reader and call this function appropriately. For example, on macOS the client can handle the @"AXEnhancedUserStructure" accessibility attribute to detect VoiceOver state changes and on Windows the client can handle WM_GETOBJECT with OBJID_CLIENT to detect accessibility readers.

For windowless browsers accessibility will be enabled in TreeOnly mode (which corresponds to kAccessibilityModeWebContentsOnly in Chromium). In this mode renderer accessibility is enabled, the full tree is computed, and events are passed to CefAccessibiltyHandler, but platform accessibility objects are not created. The client may implement platform accessibility objects using CefAccessibiltyHandler callbacks if desired.