Relanding 49339 ...

chrome/browser/renderer_host/render_widget_host_view_win.cc

Index: chrome/browser/renderer_host/render_widget_host_view_win.cc
===================================================================
--- chrome/browser/renderer_host/render_widget_host_view_win.cc	(revision 49343)
+++ chrome/browser/renderer_host/render_widget_host_view_win.cc	(working copy)
@@ -252,7 +252,6 @@
                      paint_rect.width(), paint_rect.height());
   canvas.getTopPlatformDevice().drawToHDC(paint_dc, paint_rect.x(),
                                           paint_rect.y(), NULL);
-
 }
 
 }  // namespace
@@ -284,12 +283,15 @@
       is_loading_(false),
       visually_deemphasized_(false) {
   render_widget_host_->set_view(this);
-  renderer_accessible_ =
-      CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableRendererAccessibility);
   registrar_.Add(this,
                  NotificationType::RENDERER_PROCESS_TERMINATED,
                  NotificationService::AllSources());
+
+  BOOL screenreader_running = FALSE;
+  if (SystemParametersInfo(SPI_GETSCREENREADER, 0, &screenreader_running, 0) &&
+      screenreader_running) {
+    render_widget_host_->EnableRendererAccessibility();
+  }
 }
 
 RenderWidgetHostViewWin::~RenderWidgetHostViewWin() {
@@ -1483,6 +1485,9 @@
     const webkit_glue::WebAccessibility& tree) {
   browser_accessibility_manager_.reset(
       new BrowserAccessibilityManager(m_hWnd, tree, this));
+
+  ::NotifyWinEvent(
+      IA2_EVENT_DOCUMENT_LOAD_COMPLETE, m_hWnd, OBJID_CLIENT, CHILDID_SELF);
 }
 
 void RenderWidgetHostViewWin::OnAccessibilityFocusChange(int acc_obj_id) {
@@ -1542,18 +1547,46 @@
 
 LRESULT RenderWidgetHostViewWin::OnGetObject(UINT message, WPARAM wparam,
                                              LPARAM lparam, BOOL& handled) {
-  // TODO(dmazzoni): http://crbug.com/25564 Disabling accessibility in the
-  // renderer is a temporary work-around until that bug is fixed.
-  if (!renderer_accessible_) {
+  if (lparam != OBJID_CLIENT) {
     handled = false;
     return static_cast<LRESULT>(0L);
   }
 
-  if (lparam == OBJID_CLIENT && browser_accessibility_manager_.get()) {
+  if (!browser_accessibility_manager_.get()) {
+    render_widget_host_->EnableRendererAccessibility();
+
+    if (!loading_accessible_.get()) {
+      // Create IAccessible to return while waiting for the accessibility tree
+      // from the renderer.
+      HRESULT hr = ::CreateStdAccessibleObject(
+          m_hWnd, OBJID_CLIENT, IID_IAccessible,
+          reinterpret_cast<void **>(&loading_accessible_));
+
+      // Annotate with STATE_SYSTEM_BUSY to indicate that the page is loading.
+      // We annotate the HWND, not the loading_accessible IAccessible, but the
+      // IAccessible will reflect the state annotation.
+      ScopedComPtr<IAccPropServices> pAccPropServices;
+      hr = CoCreateInstance(CLSID_AccPropServices, NULL, CLSCTX_SERVER,
+          IID_IAccPropServices, reinterpret_cast<void**>(&pAccPropServices));
+      if (SUCCEEDED(hr)) {
+        VARIANT var;
+        var.vt = VT_I4;
+        var.lVal = STATE_SYSTEM_BUSY;
+        pAccPropServices->SetHwndProp(m_hWnd, OBJID_CLIENT,
+            CHILDID_SELF, PROPID_ACC_STATE, var);
+      }
+    }
+
+    if (loading_accessible_.get()) {
+      return LresultFromObject(
+          IID_IAccessible, wparam,
+          static_cast<IAccessible*>(loading_accessible_));
+    }
+  } else {
     BrowserAccessibility* root = browser_accessibility_manager_->GetRoot();
     if (root) {
       return LresultFromObject(IID_IAccessible, wparam,
-                               static_cast<IAccessible*>(root->NewReference()));
+          static_cast<IAccessible*>(root->NewReference()));
     }
   }