Implemented a policy for centralized setting of the --disk-cache-dir flag.

chrome/browser/browser_process_impl.cc

Index: chrome/browser/browser_process_impl.cc
diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index d1e43d6e0efe40e04990287620782caa51bf9b28..45b25bd9d67f562da88d01ad48080715693cc4f5 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -906,6 +906,10 @@ void BrowserProcessImpl::CreateLocalState() {
                                    local_state_.get(), NULL);
   plugin_finder_disabled_pref_.MoveToThread(BrowserThread::IO);
 
+  // Initialize the disk cache location policy. This policy is not hot update-
+  // able so we need to have it when initializing the profiles.
+  local_state_->RegisterFilePathPref(prefs::kDiskCacheDir, FilePath());
+
   // This is observed by ChildProcessSecurityPolicy, which lives in content/
   // though, so it can't register itself.
   local_state_->RegisterListPref(prefs::kDisabledSchemes);