Extract minimal RenderViewHost interface for embedders, leaving

content/browser/accessibility/dump_accessibility_tree_browsertest.cc

Index: content/browser/accessibility/dump_accessibility_tree_browsertest.cc
diff --git a/content/browser/accessibility/dump_accessibility_tree_browsertest.cc b/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
index 334fc053b93e6ba8c2b1deecede7dfa6398c88aa..1dda61a269495dd0ab30e1dfcde6b9a011c4d55a 100644
--- a/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
+++ b/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
@@ -52,7 +52,9 @@ IN_PROC_BROWSER_TEST_F(DumpAccessibilityTreeTest,
   content::RenderWidgetHostView* host_view =
       browser()->GetSelectedWebContents()->GetRenderWidgetHostView();
   RenderWidgetHost* host = host_view->GetRenderWidgetHost();
-  RenderViewHost* view_host = static_cast<RenderViewHost*>(host);
+  // TODO(joi): Remove this dependency
+  RenderViewHostImpl* view_host =
+      static_cast<RenderViewHostImpl*>(RenderWidgetHostImpl::From(host));
   view_host->set_save_accessibility_tree_for_testing(true);
   view_host->EnableRendererAccessibility();