Prevent child frames from sending bad accessibility events.

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 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/frame_host/render_frame_host_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 661 matching lines @@
     Send(new AccessibilityMsg_FatalError(routing_id_));
   } else {
     accessibility_reset_token_ = g_next_accessibility_reset_token++;
     UMA_HISTOGRAM_COUNTS("Accessibility.FrameResetCount", 1);
     Send(new AccessibilityMsg_Reset(routing_id_, accessibility_reset_token_));
   }
 }
 
 gfx::AcceleratedWidget
     RenderFrameHostImpl::AccessibilityGetAcceleratedWidget() {
+  // Only the main frame's current frame host is connected to the native
+  // widget tree for accessibility, so return null if this is queried on
+  // any other frame.
+  if (frame_tree_node()->parent() ||
+      frame_tree_node()->current_frame_host() != this) {
+    return gfx::kNullAcceleratedWidget;
+  }
+
   RenderWidgetHostViewBase* view = static_cast<RenderWidgetHostViewBase*>(
       render_view_host_->GetWidget()->GetView());
   if (view)
     return view->AccessibilityGetAcceleratedWidget();
   return gfx::kNullAcceleratedWidget;
 }
 
 gfx::NativeViewAccessible
     RenderFrameHostImpl::AccessibilityGetNativeViewAccessible() {
   RenderWidgetHostViewBase* view = static_cast<RenderWidgetHostViewBase*>(
@@ skipping 2052 matching lines @@
 }
 
 void RenderFrameHostImpl::CreateWebBluetoothService(
     blink::mojom::WebBluetoothServiceRequest request) {
   DCHECK(!web_bluetooth_service_);
   web_bluetooth_service_.reset(
       new WebBluetoothServiceImpl(this, std::move(request)));
 }
 
 }  // namespace content