Introduce WebAccessibilityControllerImpl.

Removes accessibility-related WebCore dependencies from glue.

R=darin
TEST=none
BUG=24616

Review URL: http://codereview.chromium.org/348063

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@30986 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 591 insertions, 14 deletions

diff --git a/webkit/api/WebKit.gyp b/webkit/api/WebKit.gyp
index 9551e7f..49c8966 100644
--- a/webkit/api/WebKit.gyp
+++ b/webkit/api/WebKit.gyp
@@ -64,7 +64,7 @@
         'public/x11/WebScreenInfoFactory.h',
         'public/mac/WebInputEventFactory.h',
         'public/mac/WebScreenInfoFactory.h',
-        'public/WebAccessibilityController.h',
+        'public/WebAccessibilityCache.h',
         'public/WebAccessibilityObject.h',
         'public/WebAccessibilityRole.h',
         'public/WebApplicationCacheHost.h',
@@ -210,7 +210,9 @@
         'src/StorageNamespaceProxy.cpp',
         'src/StorageNamespaceProxy.h',
         'src/TemporaryGlue.h',
-        'src/WebAccessibilityController.cpp',
+        'src/WebAccessibilityCache.cpp',
+        'src/WebAccessibilityCacheImpl.cpp',
+        'src/WebAccessibilityCacheImpl.h',
         'src/WebAccessibilityObject.cpp',
         'src/WebBindings.cpp',
         'src/WebCache.cpp',
diff --git a/webkit/api/public/WebAccessibilityController.h b/webkit/api/public/WebAccessibilityCache.h
index 00dbd13..91992c5 100755
--- a/webkit/api/public/WebAccessibilityController.h
+++ b/webkit/api/public/WebAccessibilityCache.h
@@ -28,20 +28,32 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebAccessibilityController_h
-#define WebAccessibilityController_h
+#ifndef WebAccessibilityCache_h
+#define WebAccessibilityCache_h
 
 #include "WebCommon.h"
 
 namespace WebKit {
+    class WebView;
+    class WebAccessibilityObject;
 
-    // FIXME: Move all methods of WebAcessibilityManager here.
-    class WebAccessibilityController {
+    class WebAccessibilityCache {
     public:
-        WebAccessibilityController() {}
-        virtual ~WebAccessibilityController() {}
+        WebAccessibilityCache() {}
+        virtual ~WebAccessibilityCache() {}
 
+        static WebAccessibilityCache* create();
         static void enableAccessibility();
+
+        virtual void initialize(WebView* view) = 0;
+        virtual bool isInitialized() const = 0;
+
+        virtual WebAccessibilityObject getObjectById(int) = 0;
+        virtual bool isValidId(int) const = 0;
+        virtual int addOrGetId(const WebAccessibilityObject& object) = 0;
+
+        virtual void remove(int) = 0;
+        virtual void clear() = 0;
     };
 
 } // namespace WebKit
diff --git a/webkit/api/public/WebAccessibilityObject.h b/webkit/api/public/WebAccessibilityObject.h
index 5bfbdc1..eba5c64 100644
--- a/webkit/api/public/WebAccessibilityObject.h
+++ b/webkit/api/public/WebAccessibilityObject.h
@@ -42,6 +42,8 @@ namespace WTF { template <typename T> class PassRefPtr; }
 namespace WebKit {
     class WebAccessibilityObjectPrivate;
     class WebString;
+    struct WebPoint;
+    struct WebRect;
 
     // A container for passing around a reference to AccessibilityObject.
     class WebAccessibilityObject {
@@ -58,10 +60,39 @@ namespace WebKit {
         bool isNull() const { return m_private == 0; }
 
         WebString accessibilityDescription() const;
-        WebAccessibilityObject childAt(unsigned) const;
+        WebString actionVerb() const;
+        bool canSetFocusAttribute() const;
+
         unsigned childCount() const;
+
+        WebAccessibilityObject childAt(unsigned) const;
+        WebAccessibilityObject firstChild() const;
+        WebAccessibilityObject focusedChild() const;
+        WebAccessibilityObject lastChild() const;
+        WebAccessibilityObject nextSibling() const;
+        WebAccessibilityObject parentObject() const;
+        WebAccessibilityObject previousSibling() const;
+
+        bool isAnchor() const;
+        bool isChecked() const;
+        bool isFocused() const;
         bool isEnabled() const;
+        bool isHovered() const;
+        bool isIndeterminate() const;
+        bool isMultiSelect() const;
+        bool isOffScreen() const;
+        bool isPasswordField() const;
+        bool isPressed() const;
+        bool isReadOnly() const;
+        bool isVisited() const;
+
+        WebRect boundingBoxRect() const;
+        WebString helpText() const;
+        WebAccessibilityObject hitTest(const WebPoint&) const;
+        WebString keyboardShortcut() const;
+        bool performDefaultAction() const;
         WebAccessibilityRole roleValue() const;
+        WebString stringValue() const;
         WebString title() const;
 
 #if WEBKIT_IMPLEMENTATION
diff --git a/webkit/api/src/WebAccessibilityController.cpp b/webkit/api/src/WebAccessibilityCache.cpp
index d2df500..8a3f697 100755
--- a/webkit/api/src/WebAccessibilityController.cpp
+++ b/webkit/api/src/WebAccessibilityCache.cpp
@@ -29,7 +29,7 @@
  */
 
 #include "config.h"
-#include "WebAccessibilityController.h"
+#include "WebAccessibilityCache.h"
 
 #include "AXObjectCache.h"
 
@@ -37,7 +37,7 @@ using namespace WebCore;
 
 namespace WebKit {
 
-void WebAccessibilityController::enableAccessibility()
+void WebAccessibilityCache::enableAccessibility()
 {
     AXObjectCache::enableAccessibility();
 }
diff --git a/webkit/api/src/WebAccessibilityCacheImpl.cpp b/webkit/api/src/WebAccessibilityCacheImpl.cpp
new file mode 100644
index 0000000..232a765
--- /dev/null
+++ b/webkit/api/src/WebAccessibilityCacheImpl.cpp
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2009 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "WebAccessibilityCacheImpl.h"
+
+#include "AccessibilityObject.h"
+#include "AXObjectCache.h"
+#include "Document.h"
+#include "Frame.h"
+#include "WebAccessibilityObject.h"
+#include "WebFrameImpl.h"
+#include "WebViewImpl.h"
+
+using namespace WebCore;
+
+namespace WebKit {
+
+const int invalidObjectId = -1;
+const int firstObjectId = 1000;
+
+static PassRefPtr<AccessibilityObject> toAccessibilityObject(const WebAccessibilityObject& object)
+{
+    return object;
+}
+
+// WebView ----------------------------------------------------------------
+
+WebAccessibilityCache* WebAccessibilityCache::create()
+{
+    return new WebAccessibilityCacheImpl();
+}
+
+// WeakHandle -------------------------------------------------------------
+
+PassRefPtr<WebAccessibilityCacheImpl::WeakHandle> WebAccessibilityCacheImpl::WeakHandle::create(AccessibilityObject* object)
+{
+    // FIXME: Remove resetting ref-count from AccessibilityObjectWrapper
+    // and convert to use adoptRef.
+    return new WebAccessibilityCacheImpl::WeakHandle(object);
+}
+
+WebAccessibilityCacheImpl::WeakHandle::WeakHandle(AccessibilityObject* object)
+    : AccessibilityObjectWrapper(object)
+{
+    m_object->setWrapper(this);
+}
+
+// WebAccessibilityCacheImpl ----------------------------------------
+
+void WebAccessibilityCacheImpl::WeakHandle::detach()
+{
+    if (m_object)
+        m_object = 0;
+}
+
+WebAccessibilityCacheImpl::WebAccessibilityCacheImpl()
+    : m_nextNewId(firstObjectId)
+    , m_initialized(false)
+{
+}
+
+WebAccessibilityCacheImpl::~WebAccessibilityCacheImpl()
+{
+}
+
+void WebAccessibilityCacheImpl::initialize(WebView* view)
+{
+    AXObjectCache::enableAccessibility();
+    WebAccessibilityObject root = view->accessibilityObject();
+    if (root.isNull())
+        return;
+
+    RefPtr<AccessibilityObject> rootObject = toAccessibilityObject(root);
+
+    // Insert root in hashmaps.
+    m_objectMap.set(m_nextNewId, WeakHandle::create(rootObject.get()));
+    m_idMap.set(rootObject.get(), m_nextNewId++);
+
+    m_initialized = true;
+}
+
+WebAccessibilityObject WebAccessibilityCacheImpl::getObjectById(int id)
+{
+    ObjectMap::iterator it = m_objectMap.find(id);
+
+    if (it == m_objectMap.end() || !it->second)
+        return WebAccessibilityObject();
+
+    return WebAccessibilityObject(it->second->accessibilityObject());
+}
+
+bool WebAccessibilityCacheImpl::isValidId(int id) const
+{
+    return id >= firstObjectId;
+}
+
+void WebAccessibilityCacheImpl::remove(int id)
+{
+    ObjectMap::iterator it = m_objectMap.find(id);
+
+    if (it == m_objectMap.end())
+        return;
+
+    if (it->second) {
+        // Erase element from reverse hashmap.
+        IdMap::iterator it2 = m_idMap.find(it->second->accessibilityObject());
+        if (it2 != m_idMap.end())
+            m_idMap.remove(it2);
+    }
+
+    m_objectMap.remove(it);
+}
+
+void WebAccessibilityCacheImpl::clear()
+{
+    m_objectMap.clear();
+    m_idMap.clear();
+}
+
+int WebAccessibilityCacheImpl::addOrGetId(const WebAccessibilityObject& object) {
+    if (object.isNull())
+        return invalidObjectId;
+
+    RefPtr<AccessibilityObject> o = toAccessibilityObject(object);
+
+    IdMap::iterator it = m_idMap.find(o.get());
+
+    if (it != m_idMap.end())
+        return it->second;
+
+    // Insert new accessibility object in hashmaps and return its newly
+    // assigned accessibility object id.
+    m_objectMap.set(m_nextNewId, WeakHandle::create(o.get()));
+    m_idMap.set(o.get(), m_nextNewId);
+
+    return m_nextNewId++;
+}
+
+}
diff --git a/webkit/api/src/WebAccessibilityCacheImpl.h b/webkit/api/src/WebAccessibilityCacheImpl.h
new file mode 100644
index 0000000..1173a41
--- /dev/null
+++ b/webkit/api/src/WebAccessibilityCacheImpl.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2009 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WebAccessibilityCacheImpl_h
+#define WebAccessibilityCacheImpl_h
+
+// FIXME: Move wtf/RefCounted.h include to AccessibilityObjectWrapper.h
+// once this file is upstream.
+#include <wtf/RefCounted.h>
+#include "AccessibilityObjectWrapper.h"
+#include "WebAccessibilityCache.h"
+#include <wtf/HashMap.h>
+#include <wtf/PassRefPtr.h>
+
+namespace WebKit {
+
+// FIXME: Should be eliminated to use AXObjectCache instead.
+class WebAccessibilityCacheImpl : public WebKit::WebAccessibilityCache {
+public:
+    virtual void initialize(WebView* view);
+    virtual bool isInitialized() const { return m_initialized; }
+
+    virtual WebAccessibilityObject getObjectById(int);
+    virtual bool isValidId(int) const;
+    virtual int addOrGetId(const WebKit::WebAccessibilityObject&);
+
+    virtual void remove(int);
+    virtual void clear();
+
+protected:
+    friend class WebKit::WebAccessibilityCache;
+
+    WebAccessibilityCacheImpl();
+    ~WebAccessibilityCacheImpl();
+
+private:
+    // FIXME: This can be just part of Chromium's AccessibilityObjectWrapper.
+    class WeakHandle : public WebCore::AccessibilityObjectWrapper {
+    public:
+        static PassRefPtr<WeakHandle> create(WebCore::AccessibilityObject*);
+        virtual void detach();
+    private:
+        WeakHandle(WebCore::AccessibilityObject*);
+    };
+
+    typedef HashMap<int, RefPtr<WeakHandle> > ObjectMap;
+    typedef HashMap<WebCore::AccessibilityObject*, int> IdMap;
+
+    // Hashmap for caching of elements in use by the AT, mapping id (int) to
+    // WebAccessibilityObject.
+    ObjectMap m_objectMap;
+    // Hashmap for caching of elements in use by the AT, mapping a
+    // AccessibilityObject pointer to its id (int). Needed for reverse lookup,
+    // to ensure unnecessary duplicate entries are not created in the
+    // ObjectMap and for focus changes in WebKit.
+    IdMap m_idMap;
+
+    // Unique identifier for retrieving an accessibility object from the page's
+    // hashmaps. Id is always 0 for the root of the accessibility object
+    // hierarchy (on a per-renderer process basis).
+    int m_nextNewId;
+
+    bool m_initialized;
+};
+
+}
+
+#endif
diff --git a/webkit/api/src/WebAccessibilityObject.cpp b/webkit/api/src/WebAccessibilityObject.cpp
index f1da633..49fed03 100755
--- a/webkit/api/src/WebAccessibilityObject.cpp
+++ b/webkit/api/src/WebAccessibilityObject.cpp
@@ -29,8 +29,14 @@
  */
 
 #include "config.h"
-#include "AccessibilityObject.h"
 #include "WebAccessibilityObject.h"
+
+#include "AccessibilityObject.h"
+#include "EventHandler.h"
+#include "FrameView.h"
+#include "PlatformKeyboardEvent.h"
+#include "WebPoint.h"
+#include "WebRect.h"
 #include "WebString.h"
 
 using namespace WebCore;
@@ -62,6 +68,33 @@ WebString WebAccessibilityObject::accessibilityDescription() const
     return m_private->accessibilityDescription();
 }
 
+WebString WebAccessibilityObject::actionVerb() const
+{
+    if (!m_private)
+        return WebString();
+
+    m_private->updateBackingStore();
+    return m_private->actionVerb();
+}
+
+bool WebAccessibilityObject::canSetFocusAttribute() const
+{
+    if (!m_private)
+        return false;
+
+    m_private->updateBackingStore();
+    return m_private->canSetFocusAttribute();
+}
+
+unsigned WebAccessibilityObject::childCount() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->children().size();
+}
+
 WebAccessibilityObject WebAccessibilityObject::childAt(unsigned index) const
 {
     if (!m_private)
@@ -74,13 +107,92 @@ WebAccessibilityObject WebAccessibilityObject::childAt(unsigned index) const
     return WebAccessibilityObject(m_private->children()[index]);
 }
 
-unsigned WebAccessibilityObject::childCount() const
+WebAccessibilityObject WebAccessibilityObject::firstChild() const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    return WebAccessibilityObject(m_private->firstChild());
+}
+
+WebAccessibilityObject WebAccessibilityObject::focusedChild() const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    RefPtr<AccessibilityObject> focused = m_private->focusedUIElement();
+    if (m_private == focused.get() || focused->parentObject() == m_private)
+        return WebAccessibilityObject(focused);
+
+    return WebAccessibilityObject();
+}
+
+WebAccessibilityObject WebAccessibilityObject::lastChild() const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    return WebAccessibilityObject(m_private->lastChild());
+}
+
+
+WebAccessibilityObject WebAccessibilityObject::nextSibling() const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    return WebAccessibilityObject(m_private->nextSibling());
+}
+
+WebAccessibilityObject WebAccessibilityObject::parentObject() const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    return WebAccessibilityObject(m_private->parentObject());
+}
+
+
+WebAccessibilityObject WebAccessibilityObject::previousSibling() const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    return WebAccessibilityObject(m_private->previousSibling());
+}
+
+bool WebAccessibilityObject::isAnchor() const
 {
     if (!m_private)
         return 0;
 
     m_private->updateBackingStore();
-    return m_private->children().size();
+    return m_private->isAnchor();
+}
+
+bool WebAccessibilityObject::isChecked() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isChecked();
+}
+
+
+bool WebAccessibilityObject::isFocused() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isFocused();
 }
 
 bool WebAccessibilityObject::isEnabled() const
@@ -92,12 +204,170 @@ bool WebAccessibilityObject::isEnabled() const
     return m_private->isEnabled();
 }
 
+bool WebAccessibilityObject::isHovered() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isHovered();
+}
+
+bool WebAccessibilityObject::isIndeterminate() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isIndeterminate();
+}
+
+bool WebAccessibilityObject::isMultiSelect() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isMultiSelect();
+}
+
+bool WebAccessibilityObject::isOffScreen() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isOffScreen();
+}
+
+bool WebAccessibilityObject::isPasswordField() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isPasswordField();
+}
+
+bool WebAccessibilityObject::isPressed() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isPressed();
+}
+
+bool WebAccessibilityObject::isReadOnly() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isReadOnly();
+}
+
+bool WebAccessibilityObject::isVisited() const
+{
+    if (!m_private)
+        return 0;
+
+    m_private->updateBackingStore();
+    return m_private->isVisited();
+}
+
+WebRect WebAccessibilityObject::boundingBoxRect() const
+{
+    if (!m_private)
+        return WebRect();
+
+    m_private->updateBackingStore();
+    return m_private->documentFrameView()->contentsToWindow(m_private->boundingBoxRect());
+}
+
+WebString WebAccessibilityObject::helpText() const
+{
+    if (!m_private)
+        return WebString();
+
+    m_private->updateBackingStore();
+    return m_private->helpText();
+}
+
+WebAccessibilityObject WebAccessibilityObject::hitTest(const WebPoint& point) const
+{
+    if (!m_private)
+        return WebAccessibilityObject();
+
+    m_private->updateBackingStore();
+    IntPoint contentsPoint = m_private->documentFrameView()->windowToContents(point);
+    RefPtr<AccessibilityObject> hit = m_private->doAccessibilityHitTest(contentsPoint);
+
+    if (hit.get())
+        return WebAccessibilityObject(hit);
+
+    if (m_private->boundingBoxRect().contains(contentsPoint))
+        return *this;
+
+    return WebAccessibilityObject();
+}
+
+WebString WebAccessibilityObject::keyboardShortcut() const
+{
+    if (!m_private)
+        return WebString();
+
+    m_private->updateBackingStore();
+    String accessKey = m_private->accessKey();
+    if (accessKey.isNull())
+        return WebString();
+
+    static String modifierString;
+    if (modifierString.isNull()) {
+        unsigned modifiers = EventHandler::accessKeyModifiers();
+        // Follow the same order as Mozilla MSAA implementation:
+        // Ctrl+Alt+Shift+Meta+key. MSDN states that keyboard shortcut strings
+        // should not be localized and defines the separator as "+".
+        if (modifiers & PlatformKeyboardEvent::CtrlKey)
+            modifierString += "Ctrl+";
+        if (modifiers & PlatformKeyboardEvent::AltKey)
+            modifierString += "Alt+";
+        if (modifiers & PlatformKeyboardEvent::ShiftKey)
+            modifierString += "Shift+";
+        if (modifiers & PlatformKeyboardEvent::MetaKey)
+            modifierString += "Win+";
+    }
+
+    return modifierString + accessKey;
+}
+
+bool WebAccessibilityObject::performDefaultAction() const
+{
+    if (!m_private)
+        return false;
+
+    m_private->updateBackingStore();
+    return m_private->performDefaultAction();
+}
+
 WebAccessibilityRole WebAccessibilityObject::roleValue() const
 {
+    if (!m_private)
+        return WebKit::WebAccessibilityRoleUnknown;
+
     m_private->updateBackingStore();
     return static_cast<WebAccessibilityRole>(m_private->roleValue());
 }
 
+WebString WebAccessibilityObject::stringValue() const
+{
+    if (!m_private)
+        return WebString();
+
+    m_private->updateBackingStore();
+    return m_private->stringValue();
+}
+
 WebString WebAccessibilityObject::title() const
 {
     if (!m_private)