Revert of Revert of Migrate accessibility from RenderView to RenderFrame.

content/browser/accessibility/accessibility_tree_formatter.cc

Index: content/browser/accessibility/accessibility_tree_formatter.cc
diff --git a/content/browser/accessibility/accessibility_tree_formatter.cc b/content/browser/accessibility/accessibility_tree_formatter.cc
index cca61a5b5c64babd01fb9f316f1928aabfa23b12..97ce7fea103c8740ad9241c70c2eb81d05b05dd0 100644
--- a/content/browser/accessibility/accessibility_tree_formatter.cc
+++ b/content/browser/accessibility/accessibility_tree_formatter.cc
@@ -12,7 +12,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
-#include "content/public/browser/render_view_host.h"
+#include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/web_contents.h"
 
 namespace content {
@@ -30,12 +30,10 @@
 
 // static
 AccessibilityTreeFormatter* AccessibilityTreeFormatter::Create(
-    RenderViewHost* rvh) {
-  RenderWidgetHostViewBase* host_view = static_cast<RenderWidgetHostViewBase*>(
-      WebContents::FromRenderViewHost(rvh)->GetRenderWidgetHostView());
-
+    WebContents* web_contents) {
   BrowserAccessibilityManager* manager =
-      host_view->GetBrowserAccessibilityManager();
+      static_cast<WebContentsImpl*>(web_contents)->
+          GetRootBrowserAccessibilityManager();
   if (!manager)
     return NULL;