Rewrites renderer accessibility to not use WebAccessibilityCache.

This fixes the primary underlying cause of a number of bugs where the
browser's accessibility tree got out of sync with the renderer's accessibility
tree, which makes the page seem not functional anymore.

Splits renderer accessibility code out of render_view.cc into its own file.
All code now uses the axID directly from WebCore::AccessibilityObject rather
than WebAccessibilityCache, which can now be deleted. One implication of this
is that the top-level node can now change its ID, so we introduce a new
role ROLE_ROOT_WEB_AREA to distinguish it from an iframe's ROLE_WEB_AREA node.

To solve the problem of getting out of sync, the renderer now
maintains a tree of axIDs that reflects the state of the tree as of
the most recent message sent to the browser. Whenever a new
accessibility notification is posted, it refers to that tree to
determine precisely what information needs to be sent to the browser,
eliminating problems where the renderer was posting notifications
about nodes that the browser didn't know about.

BUG=93095,93232,92716,90787,90768
TEST=updated lots of tests

Review URL: http://codereview.chromium.org/7966013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@103249 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 11 insertions, 252 deletions

diff --git a/content/renderer/render_view.cc b/content/renderer/render_view.cc
index 7218dfe..02d3cf2 100644
--- a/content/renderer/render_view.cc
+++ b/content/renderer/render_view.cc
@@ -63,6 +63,7 @@
 #include "content/renderer/render_view_observer.h"
 #include "content/renderer/render_view_visitor.h"
 #include "content/renderer/render_widget_fullscreen_pepper.h"
+#include "content/renderer/renderer_accessibility.h"
 #include "content/renderer/renderer_webapplicationcachehost_impl.h"
 #include "content/renderer/renderer_webstoragenamespace_impl.h"
 #include "content/renderer/speech_input_dispatcher.h"
@@ -79,7 +80,6 @@
 #include "net/base/net_errors.h"
 #include "net/http/http_util.h"
 #include "ppapi/c/private/ppb_flash_net_connector.h"
-#include "third_party/WebKit/Source/WebKit/chromium/public/WebAccessibilityCache.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebAccessibilityObject.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebCString.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDataSource.h"
@@ -138,7 +138,6 @@
 #include "webkit/glue/glue_serialize.h"
 #include "webkit/glue/media/video_renderer_impl.h"
 #include "webkit/glue/password_form_dom_manager.h"
-#include "webkit/glue/webaccessibility.h"
 #include "webkit/glue/webdropdata.h"
 #include "webkit/glue/webkit_constants.h"
 #include "webkit/glue/webkit_glue.h"
@@ -163,7 +162,6 @@
 #include "skia/ext/skia_utils_mac.h"
 #endif
 
-using WebKit::WebAccessibilityCache;
 using WebKit::WebAccessibilityNotification;
 using WebKit::WebAccessibilityObject;
 using WebKit::WebApplicationCacheHost;
@@ -243,7 +241,6 @@ using webkit_glue::FormField;
 using webkit_glue::PasswordForm;
 using webkit_glue::PasswordFormDomManager;
 using webkit_glue::ResourceFetcher;
-using webkit_glue::WebAccessibility;
 
 //-----------------------------------------------------------------------------
 
@@ -274,61 +271,6 @@ static void GetRedirectChain(WebDataSource* ds, std::vector<GURL>* result) {
     result->push_back(urls[i]);
 }
 
-static bool WebAccessibilityNotificationToViewHostMsg(
-    WebAccessibilityNotification notification,
-    ViewHostMsg_AccEvent::Value* type) {
-  switch (notification) {
-    case WebKit::WebAccessibilityNotificationActiveDescendantChanged:
-      *type = ViewHostMsg_AccEvent::ACTIVE_DESCENDANT_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationCheckedStateChanged:
-      *type = ViewHostMsg_AccEvent::CHECK_STATE_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationChildrenChanged:
-      *type = ViewHostMsg_AccEvent::CHILDREN_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationFocusedUIElementChanged:
-      *type = ViewHostMsg_AccEvent::FOCUS_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationLayoutComplete:
-      *type = ViewHostMsg_AccEvent::LAYOUT_COMPLETE;
-      break;
-    case WebKit::WebAccessibilityNotificationLiveRegionChanged:
-      *type = ViewHostMsg_AccEvent::LIVE_REGION_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationLoadComplete:
-      *type = ViewHostMsg_AccEvent::LOAD_COMPLETE;
-      break;
-    case WebKit::WebAccessibilityNotificationMenuListValueChanged:
-      *type = ViewHostMsg_AccEvent::MENU_LIST_VALUE_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationRowCollapsed:
-      *type = ViewHostMsg_AccEvent::ROW_COLLAPSED;
-      break;
-    case WebKit::WebAccessibilityNotificationRowCountChanged:
-      *type = ViewHostMsg_AccEvent::ROW_COUNT_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationRowExpanded:
-      *type = ViewHostMsg_AccEvent::ROW_EXPANDED;
-      break;
-    case WebKit::WebAccessibilityNotificationScrolledToAnchor:
-      *type = ViewHostMsg_AccEvent::SCROLLED_TO_ANCHOR;
-      break;
-    case WebKit::WebAccessibilityNotificationSelectedChildrenChanged:
-      *type = ViewHostMsg_AccEvent::SELECTED_CHILDREN_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationSelectedTextChanged:
-      *type = ViewHostMsg_AccEvent::SELECTED_TEXT_CHANGED;
-      break;
-    case WebKit::WebAccessibilityNotificationValueChanged:
-      *type = ViewHostMsg_AccEvent::VALUE_CHANGED;
-      break;
-    default:
-      return false;
-  }
-  return true;
-}
-
 // If |data_source| is non-null and has a NavigationState associated with it,
 // the AltErrorPageResourceFetcher is reset.
 static void StopAltErrorPageFetcher(WebDataSource* data_source) {
@@ -381,15 +323,13 @@ RenderView::RenderView(RenderThreadBase* render_thread,
       cached_has_main_frame_horizontal_scrollbar_(false),
       cached_has_main_frame_vertical_scrollbar_(false),
       ALLOW_THIS_IN_INITIALIZER_LIST(pepper_delegate_(this)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(accessibility_method_factory_(this)),
       ALLOW_THIS_IN_INITIALIZER_LIST(cookie_jar_(this)),
       geolocation_dispatcher_(NULL),
       speech_input_dispatcher_(NULL),
       device_orientation_dispatcher_(NULL),
-      accessibility_ack_pending_(false),
-      accessibility_logging_(false),
       p2p_socket_dispatcher_(NULL),
       devtools_agent_(NULL),
+      renderer_accessibility_(NULL),
       session_storage_namespace_id_(session_storage_namespace_id),
       handling_select_range_(false) {
   routing_id_ = routing_id;
@@ -435,12 +375,6 @@ RenderView::RenderView(RenderThreadBase* render_thread,
 
   host_window_ = parent_hwnd;
 
-  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
-  if (command_line.HasSwitch(switches::kEnableAccessibility))
-    WebAccessibilityCache::enableAccessibility();
-  if (command_line.HasSwitch(switches::kEnableAccessibilityLogging))
-    accessibility_logging_ = true;
-
 #if defined(ENABLE_P2P_APIS)
   p2p_socket_dispatcher_ = new content::P2PSocketDispatcher(this);
 #endif
@@ -452,6 +386,9 @@ RenderView::RenderView(RenderThreadBase* render_thread,
 
   devtools_agent_ = new DevToolsAgent(this);
 
+  renderer_accessibility_ = new RendererAccessibility(this);
+
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kEnableMediaStream)) {
     media_stream_impl_ = new MediaStreamImpl(
         RenderThread::current()->video_capture_impl_manager());
@@ -554,16 +491,6 @@ void RenderView::RemoveObserver(RenderViewObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
-bool RenderView::RendererAccessibilityNotification::ShouldIncludeChildren() {
-  typedef ViewHostMsg_AccessibilityNotification_Params params;
-  if (type == WebKit::WebAccessibilityNotificationChildrenChanged ||
-      type == WebKit::WebAccessibilityNotificationLoadComplete ||
-      type == WebKit::WebAccessibilityNotificationLiveRegionChanged) {
-    return true;
-  }
-  return false;
-}
-
 WebKit::WebView* RenderView::webview() const {
   return static_cast<WebKit::WebView*>(webwidget());
 }
@@ -729,12 +656,6 @@ bool RenderView::OnMessageReceived(const IPC::Message& message) {
                         OnSetEditCommandsForNextKeyEvent)
     IPC_MESSAGE_HANDLER(ViewMsg_CustomContextMenuAction,
                         OnCustomContextMenuAction)
-    IPC_MESSAGE_HANDLER(ViewMsg_EnableAccessibility, OnEnableAccessibility)
-    IPC_MESSAGE_HANDLER(ViewMsg_SetAccessibilityFocus, OnSetAccessibilityFocus)
-    IPC_MESSAGE_HANDLER(ViewMsg_AccessibilityDoDefaultAction,
-                        OnAccessibilityDoDefaultAction)
-    IPC_MESSAGE_HANDLER(ViewMsg_AccessibilityNotifications_ACK,
-                        OnAccessibilityNotificationsAck)
     IPC_MESSAGE_HANDLER(ViewMsg_AsyncOpenFile_ACK, OnAsyncFileOpened)
     IPC_MESSAGE_HANDLER(ViewMsg_PpapiBrokerChannelCreated,
                         OnPpapiBrokerChannelCreated)
@@ -1270,13 +1191,6 @@ void RenderView::UpdateURL(WebFrame* frame) {
   // If we end up reusing this WebRequest (for example, due to a #ref click),
   // we don't want the transition type to persist.  Just clear it.
   navigation_state->set_transition_type(PageTransition::LINK);
-
-  // Check if the navigation was within the same page, in which case we don't
-  // want to clear the accessibility cache.
-  if (accessibility_.get() && !navigation_state->was_within_same_page()) {
-    accessibility_.reset();
-    pending_accessibility_notifications_.clear();
-  }
 }
 
 // Tell the embedding application that the title of the active page has changed
@@ -1598,43 +1512,6 @@ void RenderView::didExecuteCommand(const WebString& command_name) {
   RenderThread::RecordUserMetrics(name);
 }
 
-void RenderView::SendPendingAccessibilityNotifications() {
-  if (!accessibility_.get())
-    return;
-
-  if (pending_accessibility_notifications_.empty())
-    return;
-
-  // Send all pending accessibility notifications.
-  std::vector<ViewHostMsg_AccessibilityNotification_Params> notifications;
-  for (size_t i = 0; i < pending_accessibility_notifications_.size(); i++) {
-    RendererAccessibilityNotification& notification =
-        pending_accessibility_notifications_[i];
-    WebAccessibilityObject obj = accessibility_->getObjectById(notification.id);
-    if (!obj.isValid())
-      continue;
-
-    ViewHostMsg_AccessibilityNotification_Params param;
-    WebAccessibilityNotificationToViewHostMsg(
-        pending_accessibility_notifications_[i].type, &param.notification_type);
-    param.acc_obj = WebAccessibility(
-        obj, accessibility_.get(), notification.ShouldIncludeChildren());
-    notifications.push_back(param);
-
-#ifndef NDEBUG
-    if (accessibility_logging_) {
-      LOG(INFO) << "Accessibility update:\n"
-                << param.acc_obj.DebugString(true,
-                    routing_id_,
-                    pending_accessibility_notifications_[i].type);
-    }
-#endif
-  }
-  pending_accessibility_notifications_.clear();
-  Send(new ViewHostMsg_AccessibilityNotifications(routing_id_, notifications));
-  accessibility_ack_pending_ = true;
-}
-
 bool RenderView::handleCurrentKeyboardEvent() {
   if (edit_commands_.empty())
     return false;
@@ -1858,14 +1735,6 @@ void RenderView::focusPrevious() {
 void RenderView::focusedNodeChanged(const WebNode& node) {
   Send(new ViewHostMsg_FocusedNodeChanged(routing_id_, IsEditableNode(node)));
 
-  if (WebAccessibilityCache::accessibilityEnabled() && node.isNull()) {
-    // TODO(ctguil): Make WebKit send this notification.
-    // When focus is cleared notify accessibility that the document is focused.
-    postAccessibilityNotification(
-        webview()->accessibilityObject(),
-        WebKit::WebAccessibilityNotificationFocusedUIElementChanged);
-  }
-
   FOR_EACH_OBSERVER(RenderViewObserver, observers_, FocusedNodeChanged(node));
 }
 
@@ -1881,6 +1750,12 @@ int RenderView::historyForwardListCount() {
   return history_list_length_ - historyBackListCount() - 1;
 }
 
+void RenderView::postAccessibilityNotification(
+    const WebAccessibilityObject& obj,
+    WebAccessibilityNotification notification) {
+  renderer_accessibility_->PostAccessibilityNotification(obj, notification);
+}
+
 void RenderView::didUpdateInspectorSetting(const WebString& key,
                                            const WebString& value) {
   Send(new ViewHostMsg_UpdateInspectorSetting(routing_id_,
@@ -3740,56 +3615,6 @@ void RenderView::OnMediaPlayerActionAt(const gfx::Point& location,
     webview()->performMediaPlayerAction(action, location);
 }
 
-void RenderView::OnEnableAccessibility() {
-  if (WebAccessibilityCache::accessibilityEnabled())
-    return;
-
-  WebAccessibilityCache::enableAccessibility();
-
-  if (webview()) {
-    // It's possible that the webview has already loaded a webpage without
-    // accessibility being enabled. Initialize the browser's cached
-    // accessibility tree by sending it a 'load complete' notification.
-    postAccessibilityNotification(
-        webview()->accessibilityObject(),
-        WebKit::WebAccessibilityNotificationLoadComplete);
-  }
-}
-
-void RenderView::OnSetAccessibilityFocus(int acc_obj_id) {
-  if (!accessibility_.get())
-    return;
-
-  WebAccessibilityObject obj = accessibility_->getObjectById(acc_obj_id);
-  WebAccessibilityObject root = webview()->accessibilityObject();
-  if (!obj.isValid() || !root.isValid())
-    return;
-
-  // By convention, calling SetFocus on the root of the tree should clear the
-  // current focus. Otherwise set the focus to the new node.
-  if (accessibility_->addOrGetId(obj) == accessibility_->addOrGetId(root))
-    webview()->clearFocusedNode();
-  else
-    obj.setFocused(true);
-}
-
-void RenderView::OnAccessibilityDoDefaultAction(int acc_obj_id) {
-  if (!accessibility_.get())
-    return;
-
-  WebAccessibilityObject obj = accessibility_->getObjectById(acc_obj_id);
-  if (!obj.isValid())
-    return;
-
-  obj.performDefaultAction();
-}
-
-void RenderView::OnAccessibilityNotificationsAck() {
-  DCHECK(accessibility_ack_pending_);
-  accessibility_ack_pending_ = false;
-  SendPendingAccessibilityNotifications();
-}
-
 void RenderView::OnGetAllSavableResourceLinksForCurrentPage(
     const GURL& page_url) {
   // Prepare list to storage all savable resource links.
@@ -4099,72 +3924,6 @@ void RenderView::OnPluginImeCompositionCompleted(const string16& text,
 }
 #endif  // OS_MACOSX
 
-void RenderView::postAccessibilityNotification(
-    const WebAccessibilityObject& obj,
-    WebAccessibilityNotification notification) {
-  if (!accessibility_.get() && webview()) {
-    // Create and initialize our accessibility cache
-    accessibility_.reset(WebAccessibilityCache::create());
-    accessibility_->initialize(webview());
-
-    // Load complete should be our first notification sent. Send it manually
-    // in cases where we don't get it first to avoid focus problems.
-    // TODO(ctguil): Investigate if a different notification is a WebCore bug.
-    if (notification != WebKit::WebAccessibilityNotificationLoadComplete) {
-      postAccessibilityNotification(accessibility_->getObjectById(1000),
-          WebKit::WebAccessibilityNotificationLoadComplete);
-    }
-  }
-
-  if (!accessibility_->isCached(obj)) {
-    // The browser doesn't know about objects that are not in the cache. Send a
-    // children change for the first accestor that actually is in the cache.
-    WebAccessibilityObject parent = obj;
-    while (parent.isValid() && !accessibility_->isCached(parent))
-      parent = parent.parentObject();
-
-    DCHECK(parent.isValid() && accessibility_->isCached(parent));
-    if (!parent.isValid())
-      return;
-    postAccessibilityNotification(
-        parent, WebKit::WebAccessibilityNotificationChildrenChanged);
-
-    // The parent's children change takes care of the child's children change.
-    if (notification == WebKit::WebAccessibilityNotificationChildrenChanged)
-      return;
-  }
-
-  // Add the accessibility object to our cache and ensure it's valid.
-  RendererAccessibilityNotification acc_notification;
-  acc_notification.id = accessibility_->addOrGetId(obj);
-  acc_notification.type = notification;
-  if (acc_notification.id < 0)
-    return;
-
-  ViewHostMsg_AccEvent::Value temp;
-  if (!WebAccessibilityNotificationToViewHostMsg(notification, &temp))
-    return;
-
-  // Discard duplicate accessibility notifications.
-  for (uint32 i = 0; i < pending_accessibility_notifications_.size(); i++) {
-    if (pending_accessibility_notifications_[i].id == acc_notification.id &&
-        pending_accessibility_notifications_[i].type == acc_notification.type) {
-      return;
-    }
-  }
-  pending_accessibility_notifications_.push_back(acc_notification);
-
-  if (!accessibility_ack_pending_ && accessibility_method_factory_.empty()) {
-    // When no accessibility notifications are in-flight post a task to send
-    // the notifications to the browser. We use PostTask so that we can queue
-    // up additional notifications.
-    MessageLoop::current()->PostTask(
-        FROM_HERE,
-        accessibility_method_factory_.NewRunnableMethod(
-            &RenderView::SendPendingAccessibilityNotifications));
-  }
-}
-
 void RenderView::OnSetEditCommandsForNextKeyEvent(
     const EditCommands& edit_commands) {
   edit_commands_ = edit_commands;