[cros] RLZ tracking can be turned off via a flag file.

chrome/browser/google/google_util_chromeos.cc

Index: chrome/browser/google/google_util_chromeos.cc
diff --git a/chrome/browser/google/google_util_chromeos.cc b/chrome/browser/google/google_util_chromeos.cc
index 2892efc7240d401e517776dfc4c9dedd4ef04e96..50947e528efe7015a3a7bb1b899e6b395280428b 100644
--- a/chrome/browser/google/google_util_chromeos.cc
+++ b/chrome/browser/google/google_util_chromeos.cc
@@ -40,12 +40,24 @@ void SetBrand(const base::Closure& callback, const std::string& brand) {
   callback.Run();
 }
 
+// True if brand code has been cleared for the current session.
+bool g_brand_empty = false;
+
 }  // namespace
 
+void ClearBrandForCurrentSession() {
+  DCHECK(
+      !content::BrowserThread::IsWellKnownThread(content::BrowserThread::UI) ||
+      content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  g_brand_empty = true;
+}
+
 std::string GetBrand() {
   DCHECK(
       !content::BrowserThread::IsWellKnownThread(content::BrowserThread::UI) ||
       content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  if (g_brand_empty)
+    return std::string();
   DCHECK(g_browser_process->local_state());
   return g_browser_process->local_state()->GetString(prefs::kRLZBrand);
 }