Create a visible window with class name Chrome_RenderWidgetHostHWND which corresponds to the bounds…

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 "base/win/windows_version.h"
+#include "content/browser/accessibility/browser_accessibility_manager_win.h"
+#include "content/browser/accessibility/browser_accessibility_win.h"
+#include "ui/base/touch/touch_enabled.h"
+#include "ui/gfx/geometry/rect.h"
+
+namespace content {
+
+LegacyRenderWidgetHostHWND::LegacyRenderWidgetHostHWND(HWND parent)
+    : manager_(NULL),
+      parent_(NULL) {
+  RECT rect = {0};
+  Create(parent, rect, L"Chrome Legacy Window",
+         WS_CHILDWINDOW, WS_EX_TRANSPARENT);
+

[sky, 2014/02/05 15:22:44]

CheckWindowCreated(hwnd())

[ananta, 2014/02/05 16:35:51]

Cannot use that as this code would also run for Windows 8 ASH where child window
creation would fail.
Added some comments to make this clear. The class would be a dummy for ASH.

+  if (base::win::GetVersion() >= base::win::VERSION_WIN7 &&
+      ui::AreTouchEventsEnabled())
+    RegisterTouchWindow(hwnd(), TWF_WANTPALM);
+
+  HRESULT hr = ::CreateStdAccessibleObject(

[sky, 2014/02/05 15:22:44]

Did you intend to check the result? If not, no need to assign it.

[ananta, 2014/02/05 16:35:51]

Added a DCHECK for hr.

+      hwnd(), OBJID_WINDOW, IID_IAccessible,
+      reinterpret_cast<void **>(window_accessible_.Receive()));
+
+  if (::IsWindow(hwnd()))

[sky, 2014/02/05 15:22:44]

I don't think this if should be necessary.

[ananta, 2014/02/05 16:35:51]

Done.

+    SetParentWindow(parent);
+}
+
+LegacyRenderWidgetHostHWND::~LegacyRenderWidgetHostHWND() {
+}
+
+void LegacyRenderWidgetHostHWND::SetParentWindow(HWND parent) {
+  ::SetParent(hwnd(), parent);
+  parent_ = parent;
+}
+
+void LegacyRenderWidgetHostHWND::OnManagerDeleted() {
+  manager_ = NULL;
+}
+
+void LegacyRenderWidgetHostHWND::Show() {
+  ::ShowWindow(hwnd(), SW_SHOW);
+}
+
+void LegacyRenderWidgetHostHWND::Hide() {
+  ::ShowWindow(hwnd(), SW_HIDE);
+}
+
+void LegacyRenderWidgetHostHWND::SetBounds(const gfx::Rect& bounds) {
+  if (::IsWindow(hwnd())) {
+    ::SetWindowPos(hwnd(), NULL, bounds.x(), bounds.y(), bounds.width(),
+                   bounds.height(), 0);
+  }
+}
+
+void LegacyRenderWidgetHostHWND::Destroy() {
+  if (::IsWindow(hwnd()))

[sky, 2014/02/05 15:22:44]

Can this be moved to the destructor instead? That way this method isn't needed.

[ananta, 2014/02/05 16:35:51]

Done.

+    ::DestroyWindow(hwnd());
+  delete this;
+}
+
+void LegacyRenderWidgetHostHWND::OnFinalMessage(HWND hwnd) {
+  if (manager_)
+    manager_->OnAccessibleHwndDeleted();
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnEraseBkGnd(UINT message,
+                                                 WPARAM w_param,
+                                                 LPARAM l_param) {
+  return 1;
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnGetObject(UINT message,
+                                                WPARAM w_param,
+                                                LPARAM l_param) {
+  if (OBJID_CLIENT != l_param || !manager_)
+    return static_cast<LRESULT>(0L);
+
+  base::win::ScopedComPtr<IAccessible> root(
+      manager_->GetRoot()->ToBrowserAccessibilityWin());
+  return LresultFromObject(IID_IAccessible, w_param,
+      static_cast<IAccessible*>(root.Detach()));
+}
+
+// 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.
+LRESULT LegacyRenderWidgetHostHWND::OnKeyboardRange(UINT message,
+                                                    WPARAM w_param,
+                                                    LPARAM l_param,
+                                                    BOOL& handled) {
+  return ::SendMessage(parent_, message, w_param, l_param);
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnMouseRange(UINT message,
+                                                 WPARAM w_param,
+                                                 LPARAM l_param,
+                                                 BOOL& handled) {
+  POINT mouse_coords;
+  mouse_coords.x = GET_X_LPARAM(l_param);
+  mouse_coords.y = GET_Y_LPARAM(l_param);
+  ::MapWindowPoints(hwnd(), parent_, &mouse_coords, 1);
+  return ::SendMessage(parent_, message, w_param,
+                       MAKELPARAM(mouse_coords.x, mouse_coords.y));
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnMouseActivate(UINT message,
+                                                    WPARAM w_param,
+                                                    LPARAM l_param) {
+  // Don't pass this to DefWindowProc. That results in the WM_MOUSEACTIVATE
+  // message going all the way to the parent which then messes up state
+  // related to focused views, etc. This is because it treats this as if
+  // it lost activation.
+  // Our dummy window should not interfere with focus and activation in
+  // the parent. Return MA_ACTIVATE here ensures that focus state in the parent
+  // is preserved.
+  return MA_ACTIVATE;
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnTouch(UINT message,
+                                            WPARAM w_param,
+                                            LPARAM l_param) {
+  return ::SendMessage(parent_, message, w_param, l_param);
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnNCPaint(UINT message,
+                                              WPARAM w_param,
+                                              LPARAM l_param) {
+  return 0;
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnPaint(UINT message,
+                                            WPARAM w_param,
+                                            LPARAM l_param) {
+  PAINTSTRUCT ps = {0};
+  ::BeginPaint(hwnd(), &ps);
+  ::EndPaint(hwnd(), &ps);
+  return 0;
+}
+
+LRESULT LegacyRenderWidgetHostHWND::OnSetCursor(UINT message,
+                                                WPARAM w_param,
+                                                LPARAM l_param) {
+  return 0;
+}
+
+}  // namespace content