Rename AXObject to AXObjectImpl in modules/ and web/

docs/accessibility/overview.md

 # Accessibility Overview
 
 Accessibility means ensuring that all users, including users with disabilities,
 have equal access to software. One piece of this involves basic design
 principles such as using appropriate font sizes and color contrast,
 avoiding using color to convey important information, and providing keyboard
 alternatives for anything that is normally accomplished with a pointing device.
 However, when you see the word "accessibility" in a directory name in Chromium,
 that code's purpose is to provide full access to Chromium's UI via external
 accessibility APIs that are utilized by assistive technology.
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 actions. This API is implemented in C++ by [AutomationInternalCustomBindings],
 which is renderer-side code, and in JavaScript by the [automation API]. The API
 is defined by [automation.idl], which must be kept synchronized with
 [ax_enums.idl].
 
 [AccessibilityHostMsg_EventParams]: https://cs.chromium.org/chromium/src/content/common/accessibility_messages.h?sq=package:chromium&l=75
 [AutomationInternalCustomBindings]: https://cs.chromium.org/chromium/src/chrome/renderer/extensions/automation_internal_custom_bindings.h
 [AXContentNodeData]: https://cs.chromium.org/chromium/src/content/common/ax_content_node_data.h
 [AXLayoutObject]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/accessibility/AXLayoutObject.h
 [AXNodeObject]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/accessibility/AXNodeObject.h
-[AXObject]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/accessibility/AXObject.h
+[AXObjectImpl]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/accessibility/AXObjectImpl.h
 [AXObjectCacheImpl]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/accessibility/AXObjectCacheImpl.h
 [AXPlatformNode]: https://cs.chromium.org/chromium/src/ui/accessibility/platform/ax_platform_node.h
 [AXTreeSerializer]: https://cs.chromium.org/chromium/src/ui/accessibility/ax_tree_serializer.h
 [BlinkAXTreeSource]: https://cs.chromium.org/chromium/src/content/renderer/accessibility/blink_ax_tree_source.h
 [BrowserAccessibility]: https://cs.chromium.org/chromium/src/content/browser/accessibility/browser_accessibility.h
 [BrowserAccessibilityDelegate]: https://cs.chromium.org/chromium/src/content/browser/accessibility/browser_accessibility_manager.h?sq=package:chromium&l=64
 [BrowserAccessibilityManager]: https://cs.chromium.org/chromium/src/content/browser/accessibility/browser_accessibility_manager.h
 [LayoutObject]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/layout/LayoutObject.h
 [NativeViewAccessibility]: https://cs.chromium.org/chromium/src/ui/views/accessibility/native_view_accessibility.h
 [Node]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/dom/Node.h
 [RenderAccessibilityImpl]: https://cs.chromium.org/chromium/src/content/renderer/accessibility/render_accessibility_impl.h
 [RenderFrameHostImpl]: https://cs.chromium.org/chromium/src/content/browser/frame_host/render_frame_host_impl.h
 [ui::AXNodeData]: https://cs.chromium.org/chromium/src/ui/accessibility/ax_node_data.h
 [WebAXObject]: https://cs.chromium.org/chromium/src/third_party/WebKit/public/web/WebAXObject.h
 [automation API]: https://cs.chromium.org/chromium/src/chrome/renderer/resources/extensions/automation
 [automation.idl]: https://cs.chromium.org/chromium/src/chrome/common/extensions/api/automation.idl
 [ax_enums.idl]: https://cs.chromium.org/chromium/src/ui/accessibility/ax_enums.idl
 [chrome.automation API]: https://developer.chrome.com/extensions/automation
 [webui-js]: https://cs.chromium.org/chromium/src/ui/webui/resources/js/cr/ui/