Accessibility information from the renderer was not being returned to tools like screen readers, etc.

This was because the object implementing the root IAccessible interface did not know how to navigate
a native render view. To work around this, we now check if the underlying view is a native view in
our root IAccessible::get_accChild function and if yes we send the WM_GETOBJECT message to the
corresponding RenderWidgetHostViewWin class, which returns an IAccessible interface which then can
expose information from the renderer.

The other changes in the accessibility code are for some crashes I observed while testing the 
screen readers like nvda, the Windows screen reader which send a flurry of WM_GETOBJECT messages
leading to some race conditions.

We also ensure that the accessibility information for a view is torn down when the view is destroyed.

Fixes portions of http://code.google.com/p/chromium/issues/detail?id=13291

Bug=13291

Review URL: http://codereview.chromium.org/261044

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@28655 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 0 deletions

diff --git a/views/accessibility/view_accessibility_wrapper.cc b/views/accessibility/view_accessibility_wrapper.cc
index 7e7f5a6..989c90a 100644
--- a/views/accessibility/view_accessibility_wrapper.cc
+++ b/views/accessibility/view_accessibility_wrapper.cc
@@ -4,6 +4,8 @@
 
 #include "views/accessibility/view_accessibility_wrapper.h"
 
+#include "base/scoped_variant_win.h"
+
 #include "views/accessibility/view_accessibility.h"
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -43,6 +45,18 @@ STDMETHODIMP ViewAccessibilityWrapper::CreateDefaultInstance(REFIID iid) {
   return E_NOINTERFACE;
 }
 
+HRESULT ViewAccessibilityWrapper::Uninitialize() {
+  view_ = NULL;
+  if (accessibility_info_.get()) {
+    accessibility_info_->put_accValue(
+        ScopedVariant(kViewsUninitializeAccessibilityInstance), NULL);
+    ::CoDisconnectObject(accessibility_info_.get(), 0);
+    accessibility_info_ = NULL;
+  }
+
+  return S_OK;
+}
+
 STDMETHODIMP ViewAccessibilityWrapper::GetInstance(REFIID iid,
                                                    void** interface_ptr) {
   if (IID_IUnknown == iid || IID_IDispatch == iid || IID_IAccessible == iid) {