Add support for GetHomeDir for Mac and Windows.

base/file_util_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/file_util.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
@@ skipping 463 matching lines @@
   }
   if (use_dev_shm) {
     *path = FilePath("/dev/shm");
     return true;
   }
 #endif
   return GetTempDir(path);
 }
 #endif  // !defined(OS_MACOSX) && !defined(OS_ANDROID)
 
-#if !defined(OS_MACOSX)
+#if !defined(OS_MACOSX)  // Mac implementation is in file_util_mac.mm.
 FilePath GetHomeDir() {
 #if defined(OS_CHROMEOS)
   if (SysInfo::IsRunningOnChromeOS())
     return FilePath("/home/chronos/user");
 #endif
 
   const char* home_dir = getenv("HOME");
   if (home_dir && home_dir[0])
     return FilePath(home_dir);
 
 #if defined(OS_ANDROID)
   DLOG(WARNING) << "OS_ANDROID: Home directory lookup not yet implemented.";
 #elif defined(USE_GLIB) && !defined(OS_CHROMEOS)
-  // g_get_home_dir calls getpwent, which can fall through to LDAP calls.
-  ThreadRestrictions::AssertIOAllowed();
-
+  // g_get_home_dir calls getpwent, which can fall through to LDAP calls so
+  // this may do I/O. However, it should be rare that $HOME is not defined and
+  // this is typically called from the path service which has no threading
+  // restrictions. The path service will cache the result which limits the
+  // badness of blocking on I/O. As a result, we don't have a thread
+  // restriction here.
   home_dir = g_get_home_dir();
   if (home_dir && home_dir[0])
     return FilePath(home_dir);
 #endif
 
   FilePath rv;
   if (GetTempDir(&rv))
     return rv;
 
   // Last resort.
@@ skipping 446 matching lines @@
     result = false;
   if (IGNORE_EINTR(close(outfile)) < 0)
     result = false;
 
   return result;
 }
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace internal
 }  // namespace base