Reset accessibility if it gets out of sync.

content/renderer/accessibility/renderer_accessibility_complete.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/renderer/accessibility/renderer_accessibility_complete.h"
 
 #include <queue>
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 21 matching lines @@
 
 namespace content {
 
 RendererAccessibilityComplete::RendererAccessibilityComplete(
     RenderFrameImpl* render_frame)
     : RendererAccessibility(render_frame),
       tree_source_(render_frame),
       serializer_(&tree_source_),
       last_scroll_offset_(gfx::Size()),
       ack_pending_(false),
+      reset_token_(0),
       weak_factory_(this) {
   WebView* web_view = render_frame_->GetRenderView()->GetWebView();
   WebSettings* settings = web_view->settings();
   settings->setAccessibilityEnabled(true);
 
 #if !defined(OS_ANDROID)
   // Skip inline text boxes on Android - since there are no native Android
   // APIs that compute the bounds of a range of text, it's a waste to
   // include these in the AX tree.
   settings->setInlineTextBoxAccessibilityEnabled(true);
@@ skipping 21 matching lines @@
                         OnDoDefaultAction)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_Events_ACK,
                         OnEventsAck)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_ScrollToMakeVisible,
                         OnScrollToMakeVisible)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_ScrollToPoint,
                         OnScrollToPoint)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_SetTextSelection,
                         OnSetTextSelection)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_HitTest, OnHitTest)
+    IPC_MESSAGE_HANDLER(AccessibilityMsg_Reset, OnReset)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_FatalError, OnFatalError)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void RendererAccessibilityComplete::FocusedNodeChanged(const WebNode& node) {
   const WebDocument& document = GetMainDocument();
   if (document.isNull())
     return;
@@ skipping 127 matching lines @@
     for (size_t i = 0; i < event_msg.update.nodes.size(); ++i) {
       locations_[event_msg.update.nodes[i].id] =
           event_msg.update.nodes[i].location;
     }
 
     VLOG(0) << "Accessibility event: " << ui::ToString(event.event_type)
             << " on node id " << event_msg.id
             << "\n" << event_msg.update.ToString();
   }
 
-  Send(new AccessibilityHostMsg_Events(routing_id(), event_msgs));
+  Send(new AccessibilityHostMsg_Events(routing_id(), event_msgs, reset_token_));
+  reset_token_ = 0;

[nasko, 2014/10/03 15:58:41]

nit: I'd move this assignment in the OnReset, so when one reads the method it is
clear that reset_token_ is non-zero only for the duration of that method.

[dmazzoni, 2014/10/03 19:08:12]

Unfortunately that won't work - HandleAXEvent doesn't run synchronously, it
posts a task.

[nasko, 2014/10/06 16:39:02]

Acknowledged.

 
   if (had_layout_complete_messages)
     SendLocationChanges();
 }
 
 void RendererAccessibilityComplete::SendLocationChanges() {
   std::vector<AccessibilityHostMsg_LocationChangeParams> messages;
 
   // Do a breadth-first explore of the whole blink AX tree.
   base::hash_map<int, gfx::Rect> new_locations;
@@ skipping 166 matching lines @@
   }
 
   // By convention, calling SetFocus on the root of the tree should clear the
   // current focus. Otherwise set the focus to the new node.
   if (acc_obj_id == root.axID())
     render_frame_->GetRenderView()->GetWebView()->clearFocusedElement();
   else
     obj.setFocused(true);
 }
 
+void RendererAccessibilityComplete::OnReset(int reset_token) {
+  reset_token_ = reset_token;
+  serializer_.Reset();
+  pending_events_.clear();
+
+  const WebDocument& document = GetMainDocument();
+  if (!document.isNull())
+    HandleAXEvent(document.accessibilityObject(), ui::AX_EVENT_LAYOUT_COMPLETE);
+}
+
 void RendererAccessibilityComplete::OnFatalError() {
   CHECK(false) << "Invalid accessibility tree.";
 }
 
 }  // namespace content