Make GetUserName() return more specific error code, so that we could know how the function failed.

rlz/win/lib/process_info.cc

Index: rlz/win/lib/process_info.cc
diff --git a/rlz/win/lib/process_info.cc b/rlz/win/lib/process_info.cc
index 2511f54ab76ab3cefb12035ba5893e8a92ee1816..790561e2c59ce9a4c0eae4d798fc94a46d3fadd4 100644
--- a/rlz/win/lib/process_info.cc
+++ b/rlz/win/lib/process_info.cc
@@ -33,8 +33,15 @@ HRESULT GetCurrentUser(std::wstring* name,
   // In which case, search for and use the process handle of a running
   // Explorer.exe.)
   HANDLE token;
-  if (!::OpenProcessToken(::GetCurrentProcess(), TOKEN_QUERY, &token))
-    return E_FAIL;
+
+  HANDLE process_handle = ::GetCurrentProcess()
+  if (!process_handle)
+    CHECK(0)

[jar (doing other things), 2014/02/26 00:27:08]

Please try to compile code before sending for a review.

Please put semicolons at end of each line of code.

Don't bother doing anything else once you hit a "CHECK".

Perhaps clearer would be:
CHECK_NE(process_handle, 0);

+    return ::GetLastError()

[jar (doing other things), 2014/02/26 00:27:08]

Note that IF you used a semicolon (on line 39), since this is NOT Python, you
would run the return statement all the time, and never reach line 42.

+
+  if (!::OpenProcessToken(process_handle, TOKEN_QUERY, &token))
+    CHECK(0)
+    return ::GetLastError()
 
   base::win::ScopedHandle scoped_process_token(token);
 
@@ -50,11 +57,13 @@ HRESULT GetCurrentUser(std::wstring* name,
 
   token_user_bytes.reset(new char[token_user_size]);
   if (!token_user_bytes.get())
+    CHECK(0)
     return E_OUTOFMEMORY;
 
   if (!::GetTokenInformation(token, TokenUser, token_user_bytes.get(),
                              token_user_size, &token_user_size2)) {
-    return E_FAIL;
+    CHECK(0)
+    return ::GetLastError();
   }
 
   WCHAR user_name[UNLEN + 1];  // max username length
@@ -65,11 +74,13 @@ HRESULT GetCurrentUser(std::wstring* name,
   TOKEN_USER* token_user =
       reinterpret_cast<TOKEN_USER*>(token_user_bytes.get());
   if (!token_user)
-    return E_FAIL;
+    CHECK(0)
+    return ::GetLastError();
   PSID user_sid = token_user->User.Sid;
   if (!::LookupAccountSidW(NULL, user_sid, user_name, &user_name_size,
                            domain_name, &domain_name_size, &sid_type)) {
-    return E_FAIL;
+    CHECK(0)
+    return ::GetLastError();
   }
 
   if (name != NULL) {