Add support for faster, more limited accessibility modes.

content/renderer/accessibility/blink_ax_tree_source.h

Index: content/renderer/accessibility/blink_ax_tree_source.h
diff --git a/content/renderer/accessibility/blink_ax_tree_source.h b/content/renderer/accessibility/blink_ax_tree_source.h
index aecc61ffcc429c66666ff14d499c843edb4a6993..ce62b6091ae825a97c611469417b581124281f7c 100644
--- a/content/renderer/accessibility/blink_ax_tree_source.h
+++ b/content/renderer/accessibility/blink_ax_tree_source.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 
+#include "content/common/accessibility_mode_enums.h"
 #include "content/common/ax_content_node_data.h"
 #include "third_party/WebKit/public/web/WebAXObject.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
@@ -36,7 +37,8 @@ class BlinkAXTreeSource
                               AXContentNodeData,
                               AXContentTreeData> {
  public:
-  BlinkAXTreeSource(RenderFrameImpl* render_frame);
+  BlinkAXTreeSource(RenderFrameImpl* render_frame,
+                    AccessibilityMode mode);
   ~BlinkAXTreeSource() override;
 
   // Freeze caches the document, accessibility root, and current focused
@@ -108,6 +110,8 @@ class BlinkAXTreeSource
 
   RenderFrameImpl* render_frame_;
 
+  AccessibilityMode accessibility_mode_;
+
   // An explicit root to use, otherwise it's taken from the WebDocument.
   blink::WebAXObject explicit_root_;