dart:io | Add Directory.CreateSystemTemp(template) and change Directory.CreateTemp(template).

runtime/bin/directory_win.cc

Index: runtime/bin/directory_win.cc
diff --git a/runtime/bin/directory_win.cc b/runtime/bin/directory_win.cc
index f5f77bd99dc568fb51a6b9087763e7c0217b8345..1995972eff951d79df8d9ad24bfdccdc1c351463 100644
--- a/runtime/bin/directory_win.cc
+++ b/runtime/bin/directory_win.cc
@@ -383,30 +383,26 @@ bool Directory::Create(const char* dir_name) {
 }
 
 
-char* Directory::CreateTemp(const char* const_template) {
+char* Directory::CreateTemp(const char* const_template, bool system) {
   // Returns a new, unused directory name, modifying the contents of
   // dir_template.  Creates this directory, with a default security
   // descriptor inherited from its parent directory.
   // The return value must be freed by the caller.
   PathBuffer path;
-  if (0 == strncmp(const_template, "", 1)) {
+  if (system) {
     path.Reset(GetTempPathW(MAX_PATH, path.AsStringW()));
     if (path.length() == 0) {
       return NULL;
     }
-  } else {
-    const wchar_t* system_template = StringUtils::Utf8ToWide(const_template);
-    path.AddW(system_template);
-    free(const_cast<wchar_t*>(system_template));
   }
-  // Length of tempdir-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx is 44.
-  if (path.length() > MAX_PATH - 44) {
+  const wchar_t* system_template = StringUtils::Utf8ToWide(const_template);
+  path.AddW(system_template);
+  free(const_cast<wchar_t*>(system_template));
+
+  // Length of -xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx is 37.
+  if (path.length() > MAX_PATH - 37) {
     return NULL;
   }
-  if ((path.AsStringW())[path.length() - 1] == L'\\') {
-    // No base name for the directory - use "tempdir".
-    path.AddW(L"tempdir");
-  }
 
   UUID uuid;
   RPC_STATUS status = UuidCreateSequential(&uuid);