Added a class acting as a fake caret for accessibility.

content/browser/renderer_host/legacy_render_widget_host_win.cc

 // Copyright (c) 2014 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/browser/renderer_host/legacy_render_widget_host_win.h"
 
 #include <memory>
 
 #include "base/command_line.h"
 #include "base/win/win_util.h"
 #include "base/win/windows_version.h"
 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
 #include "content/browser/accessibility/browser_accessibility_win.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
 #include "content/public/common/content_switches.h"
+#include "ui/accessibility/platform/ax_fake_caret_win.h"
 #include "ui/base/view_prop.h"
 #include "ui/base/win/internal_constants.h"
 #include "ui/base/win/window_event_target.h"
 #include "ui/display/win/screen_win.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/win/direct_manipulation.h"
 
 namespace content {
 
 // A custom MSAA object id used to determine if a screen reader or some
@@ skipping 135 matching lines @@
 
   if (kIdScreenReaderHoneyPot == obj_id) {
     // When an MSAA client has responded to our fake event on this id,
     // enable basic accessibility support. (Full screen reader support is
     // detected later when specific more advanced APIs are accessed.)
     BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
         AccessibilityMode::kNativeAPIs | AccessibilityMode::kWebContents);
     return static_cast<LRESULT>(0L);
   }
 
-  if (static_cast<DWORD>(OBJID_CLIENT) != obj_id || !host_)
+  if (!host_)
     return static_cast<LRESULT>(0L);
 
-  RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(
-      host_->GetRenderWidgetHost());
-  if (!rwhi)
-    return static_cast<LRESULT>(0L);
+  if (static_cast<DWORD>(OBJID_CLIENT) == obj_id) {
+    RenderWidgetHostImpl* rwhi =
+        RenderWidgetHostImpl::From(host_->GetRenderWidgetHost());
+    if (!rwhi)
+      return static_cast<LRESULT>(0L);
 
-  BrowserAccessibilityManagerWin* manager =
-      static_cast<BrowserAccessibilityManagerWin*>(
-          rwhi->GetRootBrowserAccessibilityManager());
-  if (!manager)
-    return static_cast<LRESULT>(0L);
+    BrowserAccessibilityManagerWin* manager =
+        static_cast<BrowserAccessibilityManagerWin*>(
+            rwhi->GetRootBrowserAccessibilityManager());
+    if (!manager)
+      return static_cast<LRESULT>(0L);
 
-  base::win::ScopedComPtr<IAccessible> root(
-      ToBrowserAccessibilityWin(manager->GetRoot()));
-  return LresultFromObject(IID_IAccessible, w_param,
-      static_cast<IAccessible*>(root.Detach()));
+    base::win::ScopedComPtr<IAccessible> root(
+        ToBrowserAccessibilityWin(manager->GetRoot()));
+    return LresultFromObject(IID_IAccessible, w_param,
+                             static_cast<IAccessible*>(root.Detach()));
+  }
+
+  if (static_cast<DWORD>(OBJID_CARET) == obj_id && host_->HasFocus()) {
+    // Used by some assistive software to retrieve the location of the caret.
+    ui::AXFakeCaretWin* fake_caret = ui::g_ax_fake_caret_win.Pointer();
+    DCHECK(fake_caret);
+    base::win::ScopedComPtr<IAccessible> fake_caret_accessible =
+        fake_caret->GetCaret();
+    ;
+    return LresultFromObject(IID_IAccessible, w_param,
+                             fake_caret_accessible.Detach());
+  }
+
+  return static_cast<LRESULT>(0L);
 }
 
 // We send keyboard/mouse/touch messages to the parent window via SendMessage.
 // While this works, this has the side effect of converting input messages into
 // sent messages which changes their priority and could technically result
 // in these messages starving other messages in the queue. Additionally
 // keyboard/mouse hooks would not see these messages. The alternative approach
 // is to set and release capture as needed on the parent to ensure that it
 // receives all mouse events. However that was shelved due to possible issues
 // with capture changes.
@@ skipping 220 matching lines @@
       direct_manipulation_helper_->Activate(hwnd());
     } else if (window_pos->flags & SWP_HIDEWINDOW) {
       direct_manipulation_helper_->Deactivate(hwnd());
     }
   }
   SetMsgHandled(FALSE);
   return 0;
 }
 
 }  // namespace content