Don't turn on accessibility automatically on Linux.

content/browser/renderer_host/render_widget_host_view_gtk.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_gtk.h"
 
 // If this gets included after the gtk headers, then a bunch of compiler
 // errors happen because of a "#define Status int" in Xlib.h, which interacts
 // badly with net::URLRequestStatus::Status.
 #include "content/common/view_messages.h"
@@ skipping 1481 matching lines @@
     browser_accessibility_manager_.reset(
         BrowserAccessibilityManager::CreateEmptyDocument(
             parent,
             static_cast<content::AccessibilityNodeData::State>(0),
             this));
   }
   browser_accessibility_manager_->OnAccessibilityNotifications(params);
 }
 
 AtkObject* RenderWidgetHostViewGtk::GetAccessible() {
-  RenderWidgetHostImpl::From(GetRenderWidgetHost())->
-      SetAccessibilityMode(AccessibilityModeComplete);
-
   if (!browser_accessibility_manager_.get()) {
     GtkWidget* parent = gtk_widget_get_parent(view_.get());
     browser_accessibility_manager_.reset(
         BrowserAccessibilityManager::CreateEmptyDocument(
             parent,
             static_cast<content::AccessibilityNodeData::State>(0),
             this));
   }
   BrowserAccessibilityGtk* root =
       browser_accessibility_manager_->GetRoot()->ToBrowserAccessibilityGtk();
 
   atk_object_set_role(root->GetAtkObject(), ATK_ROLE_HTML_CONTAINER);
   return root->GetAtkObject();
 }