Added a class acting as a fake caret for accessibility.

ui/views/win/hwnd_message_handler.cc

Index: ui/views/win/hwnd_message_handler.cc
diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index 94ba71385f4323bd06674ea29a4fb9beabdf41cf..9a84ac8aae233049cd9bd5e66efa25bcb2a6148d 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -20,8 +20,12 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
+#include "base/win/scoped_comptr.h"
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/windows_version.h"
+#include "ui/accessibility/platform/ax_fake_caret_win.h"
+#include "ui/accessibility/platform/ax_platform_node_win.h"
+#include "ui/base/ime/input_method_client.h"
 #include "ui/base/view_prop.h"
 #include "ui/base/win/internal_constants.h"
 #include "ui/base/win/lock_state.h"
@@ -385,6 +389,9 @@ void HWNDMessageHandler::Init(HWND parent, const gfx::Rect& bounds) {
                             ui::WindowEventTarget::kWin32InputEventTarget,
                             static_cast<ui::WindowEventTarget*>(this)));
 
+  ax_fake_caret_ = std::make_unique<ui::AXFakeCaretWin>(hwnd());
+  delegate_->AddInputMethodObserver();
+
   // Direct Manipulation is enabled on Windows 10+. The CreateInstance function
   // returns NULL if Direct Manipulation is not available.
   direct_manipulation_helper_ =
@@ -929,6 +936,7 @@ LRESULT HWNDMessageHandler::OnWndProc(UINT message,
     delegate_->PostHandleMSG(message, w_param, l_param);
     if (message == WM_NCDESTROY) {
       RestoreEnabledIfNecessary();
+      delegate_->RemoveInputMethodObserver();
       delegate_->HandleDestroyed();
     }
   }
@@ -939,6 +947,13 @@ LRESULT HWNDMessageHandler::OnWndProc(UINT message,
   return result;
 }
 
+void OnCaretBoundsChanged(const TextInputClient* client) {
+  DCHECK(ax_fake_caret_);
+  const gfx::Rect dip_screen_bounds(client->GetCaretBounds());
+  const gfx::Rect screen_bounds = display::win::ScreenWin::DIPToScreenRect(hwnd(), dip_screen_bounds);
+  ax_fake_caret_->MoveCaretTo(screen_bounds);
+}
+
 LRESULT HWNDMessageHandler::HandleMouseMessage(unsigned int message,
                                                WPARAM w_param,
                                                LPARAM l_param,
@@ -1521,10 +1536,14 @@ LRESULT HWNDMessageHandler::OnGetObject(UINT message,
     // Retrieve MSAA dispatch object for the root view.
     base::win::ScopedComPtr<IAccessible> root(
         delegate_->GetNativeViewAccessible());
-
-    // Create a reference that MSAA will marshall to the client.
     reference_result = LresultFromObject(IID_IAccessible, w_param,
         static_cast<IAccessible*>(root.Detach()));
+  } else if (static_cast<DWORD>(OBJID_CARET) == obj_id) {

[dmazzoni, 2017/04/27 05:07:32]

Only if focused???

+    DCHECK(ax_fake_caret_);
+    base::win::ScopedComPtr<IAccessible> fake_caret_accessible =
+        ax_fake_caret_->GetCaret();
+    reference_result = LresultFromObject(IID_IAccessible, w_param,
+                                         fake_caret_accessible.Detach());
   }
 
   return reference_result;