[Sync] Remove unneeded 'using syncer::' lines and 'syncer::' scopings

sync/engine/throttled_data_type_tracker.h

Index: sync/engine/throttled_data_type_tracker.h
diff --git a/sync/engine/throttled_data_type_tracker.h b/sync/engine/throttled_data_type_tracker.h
index 8db5061e7e7aa972a8213c790144a889282770e0..e2a40bffc564ecc9554d2e1b17e90db9b3e14f65 100644
--- a/sync/engine/throttled_data_type_tracker.h
+++ b/sync/engine/throttled_data_type_tracker.h
@@ -22,15 +22,14 @@ class ThrottledDataTypeTracker {
   ~ThrottledDataTypeTracker();
 
   // Throttles a set of data types until the specified time is reached.
-  void SetUnthrottleTime(syncer::ModelTypeSet types,
-                         const base::TimeTicks& time);
+  void SetUnthrottleTime(ModelTypeSet types, const base::TimeTicks& time);
 
   // Given an input of the current time (usually from time::Now()), removes from
   // the set of throttled types any types whose throttling period has expired.
   void PruneUnthrottledTypes(const base::TimeTicks& time);
 
   // Returns the set of types which are currently throttled.
-  syncer::ModelTypeSet GetThrottledTypes() const;
+  ModelTypeSet GetThrottledTypes() const;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ThrottledDataTypeTrackerTest,
@@ -38,7 +37,7 @@ class ThrottledDataTypeTracker {
   FRIEND_TEST_ALL_PREFIXES(ThrottledDataTypeTrackerTest,
                            GetCurrentlyThrottledTypesTest);
 
-  typedef std::map<syncer::ModelType, base::TimeTicks> UnthrottleTimes;
+  typedef std::map<ModelType, base::TimeTicks> UnthrottleTimes;
 
   // This is a map from throttled data types to the time at which they can be
   // unthrottled.