Tweak PathProviderPosix's FILE_EXE and FILE_MODULE handling on FreeBSD.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/8361011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@107134 0039d316-1c4b-4281-b951-d872f2087c98

base/base_paths_linux.cc

@@ -50,13 +50,14 @@ bool PathProviderPosix(int key, FilePath* result) {
       int name[] = { CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1 };
       char bin_dir[PATH_MAX + 1];
       size_t length = sizeof(bin_dir);
+      // Upon return, |length| is the number of bytes written to |bin_dir|
+      // including the string terminator.
       int error = sysctl(name, 4, bin_dir, &length, NULL, 0);
-      if (error < 0 || length == 0 || strlen(bin_dir) == 0) {
+      if (error < 0 || length <= 1) {
         NOTREACHED() << "Unable to resolve path.";
         return false;
       }
-      bin_dir[strlen(bin_dir)] = 0;
-      *result = FilePath(bin_dir);
+      *result = FilePath(FilePath::StringType(bin_dir, length - 1));
       return true;
 #elif defined(OS_SOLARIS)
       char bin_dir[PATH_MAX + 1];