Only show notification for low 3g data for the last data-based plan....

chrome/browser/chromeos/cros/network_library.h

Index: chrome/browser/chromeos/cros/network_library.h
===================================================================
--- chrome/browser/chromeos/cros/network_library.h	(revision 74304)
+++ chrome/browser/chromeos/cros/network_library.h	(working copy)
@@ -200,6 +200,8 @@
   string16 GetPlanExpiration() const;
   // Formats plan usage info.
   string16 GetUsageInfo() const;
+  // Returns a unique string for this plan that can be used for comparisons.
+  std::string GetUniqueIdentifier() const;
   base::TimeDelta remaining_time() const;
   int64 remaining_minutes() const;
   int64 remaining_data() const;