ChromeOS: Creates XDG_RUNTIME_DIR if missing.

On chromeos-chrome on Linux for development purpose,
if XDG_RUNTIME_DIR is set, but it is missing,
create it.

Bug: 1107789
Test: Ran locally.
Change-Id: I42086e71fed05976f40508c86f2c5644dd565a17
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2310030
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790454}

components/exo/wayland/server.cc

@@ -60,6 +60,7 @@
 #include "ui/display/screen.h"
 
 #if defined(OS_CHROMEOS)
+#include "base/system/sys_info.h"
 #include "components/exo/wayland/wl_shell.h"
 #include "components/exo/wayland/xdg_shell.h"
 #include "components/exo/wayland/zcr_color_space.h"
@@ -237,12 +238,23 @@ Server::~Server() {
 std::unique_ptr<Server> Server::Create(Display* display) {
   std::unique_ptr<Server> server(new Server(display));
 
-  char* runtime_dir = getenv("XDG_RUNTIME_DIR");
-  if (!runtime_dir) {
+  char* runtime_dir_str = getenv("XDG_RUNTIME_DIR");
+  if (!runtime_dir_str) {
     LOG(ERROR) << "XDG_RUNTIME_DIR not set in the environment";
     return nullptr;
   }
 
+  const base::FilePath runtime_dir(runtime_dir_str);
+#if defined(OS_CHROMEOS)
+  // On debugging chromeos-chrome on linux platform,
+  // try to ensure the directory if missing.
+  if (!base::SysInfo::IsRunningOnChromeOS()) {
+    CHECK(base::DirectoryExists(runtime_dir) ||
+          base::CreateDirectory(runtime_dir))
+        << "Failed to create XDG_RUNTIME_DIR";
+  }
+#endif  // defined(OS_CHROMEOS)
+
   std::string socket_name(kSocketName);
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kWaylandServerSocket)) {