Update default WriteFile permissions to 0640

BUG=362887

Review URL: https://codereview.chromium.org/290143005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274593 0039d316-1c4b-4281-b951-d872f2087c98

base/file_util_posix.cc

@@ -669,7 +669,7 @@ int ReadFile(const FilePath& filename, char* data, int max_size) {
 
 int WriteFile(const FilePath& filename, const char* data, int size) {
   ThreadRestrictions::AssertIOAllowed();
-  int fd = HANDLE_EINTR(creat(filename.value().c_str(), 0666));
+  int fd = HANDLE_EINTR(creat(filename.value().c_str(), 0640));
   if (fd < 0)
     return -1;