replace COMPILE_ASSERT with static_assert in ui/

ui/platform_window/x11/x11_window.cc

Index: ui/platform_window/x11/x11_window.cc
diff --git a/ui/platform_window/x11/x11_window.cc b/ui/platform_window/x11/x11_window.cc
index e86cf3c9a09cf6631f6ffd6f5672dd79190d4a21..c2706542f4df23d703c8dc67944a3d8ea8daa94f 100644
--- a/ui/platform_window/x11/x11_window.cc
+++ b/ui/platform_window/x11/x11_window.cc
@@ -173,7 +173,8 @@ void X11Window::Show() {
   // Likewise, the X server needs to know this window's pid so it knows which
   // program to kill if the window hangs.
   // XChangeProperty() expects "pid" to be long.
-  COMPILE_ASSERT(sizeof(long) >= sizeof(pid_t), pid_t_bigger_than_long);
+  static_assert(sizeof(long) >= sizeof(pid_t),
+                "pid_t should not be larger than long");
   long pid = getpid();
   XChangeProperty(xdisplay_,
                   xwindow_,