Use a better registration suffix that will always be unique while respecting the MSDN rules.

base/win/win_util.cc

Index: base/win/win_util.cc
diff --git a/base/win/win_util.cc b/base/win/win_util.cc
index 2f2e7dc76214ca9ad8b4b2fae993f2688b1cb649..8ce89c212b049e84fcb8eb1af126ad6f7b6d74c8 100644
--- a/base/win/win_util.cc
+++ b/base/win/win_util.cc
@@ -113,6 +113,40 @@ bool GetUserSidString(std::wstring* user_sid) {
   return true;
 }
 
+bool GetUserSidBase16Encoded(string16* encoded_sid) {
+  // Get the current token.
+  HANDLE token = NULL;
+  if (!::OpenProcessToken(::GetCurrentProcess(), TOKEN_QUERY, &token))
+    return false;
+  base::win::ScopedHandle token_scoped(token);
+
+  DWORD size = sizeof(TOKEN_USER) + SECURITY_MAX_SID_SIZE;
+  scoped_array<BYTE> user_bytes(new BYTE[size]);
+  TOKEN_USER* user = reinterpret_cast<TOKEN_USER*>(user_bytes.get());
+
+  if (!::GetTokenInformation(token, TokenUser, user, size, &size))
+    return false;
+
+  if (!user->User.Sid)
+    return false;

[gab, 2012/06/21 05:55:41]

I would have preferred to copy this common functionality (copied from the
function above) to a common function, but it was a pain with the PSID, PISID,
SID*, and all the types Windows gives to those things... maybe you can help me
with that tomorrow if you want.

+
+  // This method and its callers assume the resulting encoding will be
+  // exactly 24 characters.
+  COMPILE_ASSERT(sizeof(SID) == 12, size_of_SID_struct_is_not_as_expected_);

[gab, 2012/06/21 05:55:41]

This seems safe, but I'll need to read documentation some more...

+  static const size_t kExpectedEncodedLength = sizeof(SID) * 2;
+  encoded_sid->reserve(kExpectedEncodedLength);
+
+  byte* p = static_cast<byte*>(user->User.Sid);
+  for (int i = 0; i < sizeof(SID); ++i, ++p) {
+    encoded_sid->push_back('A' + (*p & 0xf));
+    encoded_sid->push_back('A' + ((*p & 0xf0) >> 4));
+  }
+
+  DCHECK_EQ(encoded_sid->length(), kExpectedEncodedLength);
+
+  return true;
+}
+
 bool IsShiftPressed() {
   return (::GetKeyState(VK_SHIFT) & 0x8000) == 0x8000;
 }