[Windows Sandbox] MITIGATION_EXTENSION_POINT_DISABLE support for children.

sandbox/win/tests/integration_tests/hooking_win_proc.cc

+// Copyright (c) 2016 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 <windows.h>
+
+namespace {
+
+const wchar_t* class_name = L"myWindowClass";
+// WinProc event name
+const wchar_t* winproc_event = L"ChromeExtensionTestEvent";
+
+}  // namespace
+
+LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
+  // Injected keystroke via PostThreadMessage won't be dispatched to here.
+  // Have to use SendMessage or SendInput to trigger the keyboard hook.
+  switch (msg) {
+    case WM_KEYDOWN:
+      break;
+    case WM_KEYUP:
+      break;
+    case WM_CLOSE:
+      ::DestroyWindow(hwnd);
+      break;
+    case WM_DESTROY:
+      ::PostQuitMessage(0);
+      break;
+    default:
+      return ::DefWindowProc(hwnd, msg, wParam, lParam);
+  }
+  return 0;
+}
+
+int WINAPI WinMain(HINSTANCE hInstance,
+                   HINSTANCE hPrevInstance,
+                   LPSTR lpCmdLine,
+                   int nCmdShow) {
+  WNDCLASSEX wc;
+  HWND hwnd;
+  MSG msg;
+
+  // Our parent should have set up this event already.
+  HANDLE event = ::OpenEventW(EVENT_MODIFY_STATE, FALSE, winproc_event);
+  if (event == NULL || event == INVALID_HANDLE_VALUE)
+    return 1;
+
+  // Step 1: Registering the Window Class.
+  wc.cbSize = sizeof(WNDCLASSEX);
+  wc.style = 0;
+  wc.lpfnWndProc = WndProc;
+  wc.cbClsExtra = 0;
+  wc.cbWndExtra = 0;
+  wc.hInstance = hInstance;
+  wc.hIcon = ::LoadIcon(NULL, IDI_APPLICATION);
+  wc.hCursor = ::LoadCursor(NULL, IDC_ARROW);
+  wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
+  wc.lpszMenuName = NULL;
+  wc.lpszClassName = class_name;
+  wc.hIconSm = ::LoadIcon(NULL, IDI_APPLICATION);
+
+  if (!::RegisterClassEx(&wc))
+    return 1;
+
+  // Step 2: Creating the Window.
+  hwnd =
+      ::CreateWindowExW(WS_EX_CLIENTEDGE, class_name,
+                      L"ChromeMitigationTests", WS_OVERLAPPEDWINDOW,
+                      CW_USEDEFAULT, CW_USEDEFAULT, 240, 120, NULL, NULL,
+                      hInstance, NULL);
+
+  if (hwnd == NULL)
+    return 1;
+
+  ::ShowWindow(hwnd, nCmdShow);
+  ::UpdateWindow(hwnd);
+
+  // Step 3: Let 'em know we're up and running.
+  ::SetEvent(event);
+
+  // Step 4: The Message Loop
+  // WM_QUIT results in a 0 value from GetMessageW,
+  // breaking the loop.
+  while (::GetMessageW(&msg, NULL, 0, 0) > 0) {
+    ::TranslateMessage(&msg);
+    ::DispatchMessageW(&msg);
+  }
+
+  ::SetEvent(event);
+  ::CloseHandle(event);
+
+  return msg.wParam;
+}