cashew: reset local counter on plan transition

src/data_plan.h

Index: src/data_plan.h
diff --git a/src/data_plan.h b/src/data_plan.h
index 4a1fe50a6bf376068ceabf4d0d0bd5ce66441895..af242bb759935294cd2672086630661e6a844248 100644
--- a/src/data_plan.h
+++ b/src/data_plan.h
@@ -20,7 +20,10 @@
 namespace cashew {
 
 class DataPlan;
+class Device;
 class Policy;
+class Service;
+class ServiceManager;
 
 // byte count
 // TODO(vlaviano): this should be a uint64, but libcros/Chrome expects this
@@ -105,6 +108,17 @@ class DataPlan {
     // returns NULL if list is empty or contains no active plans
     static DataPlan* GetActivePlan(const DataPlanList& data_plans);
 
+    // event handler for |service's| local byte counter on |device|
+    // updates active plans in |data_plans| based on the |rx_bytes| and
+    //   |tx_bytes| values gathered during the most recent sample interval
+    // notifies |service_manager| if an active plan is completely consumed
+    // returns true if any plans were updated and false otherwise
+    // |data_plans|, |service|, |service_manager| and |device| must not be NULL
+    static bool OnByteCounterUpdate(DataPlanList *data_plans, Service *service,
+                                    ServiceManager *service_manager,
+                                    Device *device, uint64 rx_bytes,
+                                    uint64 tx_bytes);
+
   private:
     // human-readable plan name
     const std::string name_;