Multi-Profiles: Pass profile directories by reference

willchan pointed out that NewRunnableFunction will copy parameters even if the method signature contains references. See:
http://codereview.chromium.org/7321011/diff/2001/chrome/browser/profiles/profile_manager.cc#newcode46

BUG=
TEST=


Review URL: http://codereview.chromium.org/7328021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@91867 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/profiles/profile_manager.cc

@@ -43,9 +43,9 @@
 
 namespace {
 
-void DeleteProfileDirectories(std::vector<FilePath> paths) {
+void DeleteProfileDirectories(const std::vector<FilePath>& paths) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  for (std::vector<FilePath>::iterator it = paths.begin();
+  for (std::vector<FilePath>::const_iterator it = paths.begin();
        it != paths.end(); ++it) {
     file_util::Delete(*it, true);
   }