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

chrome/browser/google/google_util_chromeos.h

Index: chrome/browser/google/google_util_chromeos.h
diff --git a/chrome/browser/google/google_util_chromeos.h b/chrome/browser/google/google_util_chromeos.h
index 94443ee30dfc8633707f60a8762a93fdaac6ed91..5a90eab5cf3882dc2ef300da347f93197db7f4c6 100644
--- a/chrome/browser/google/google_util_chromeos.h
+++ b/chrome/browser/google/google_util_chromeos.h
@@ -16,6 +16,10 @@ namespace chromeos {
 // partner. Returns empty string if the information is not available.
 std::string GetBrand();
 
+// Clears brand code for the current session (not persisted through browser
+// restart). Future calls to GetBrand() will return an empty string.
+void ClearBrandForCurrentSession();
+
 // Reads the brand code from a board-specific file and stores it to Local State.
 // |callback| is invoked on the calling thread after that.
 void SetBrandFromFile(const base::Closure& callback);