(Fix landed) Revert of [CrOS Tether] Create HostScanCache, which caches scan results and inserts...

chromeos/components/tether/tether_host_response_recorder.h

Index: chromeos/components/tether/tether_host_response_recorder.h
diff --git a/chromeos/components/tether/tether_host_response_recorder.h b/chromeos/components/tether/tether_host_response_recorder.h
index fed179e8c1dc0300fd5b6cb330452ddf5f00b9b9..f87dd936ccc7777b3ef6aa67c41d0b0069739955 100644
--- a/chromeos/components/tether/tether_host_response_recorder.h
+++ b/chromeos/components/tether/tether_host_response_recorder.h
@@ -9,7 +9,6 @@
 #include <vector>
 
 #include "base/macros.h"
-#include "base/observer_list.h"
 #include "components/cryptauth/remote_device.h"
 
 class PrefService;
@@ -25,22 +24,14 @@
 // Responses can be retrieved at a later time via getter methods.
 class TetherHostResponseRecorder {
  public:
-  class Observer {
-   public:
-    virtual void OnPreviouslyConnectedHostIdsChanged() = 0;
-  };
+  // Note: The PrefService* passed here must be created using the same registry
+  // passed to RegisterPrefs().
+  TetherHostResponseRecorder(PrefService* pref_service);
+  virtual ~TetherHostResponseRecorder();
 
   // Registers the prefs used by this class to |registry|. Must be called before
   // this class is utilized.
   static void RegisterPrefs(PrefRegistrySimple* registry);
-
-  // Note: The PrefService* passed here must be created using the same registry
-  // passed to RegisterPrefs().
-  explicit TetherHostResponseRecorder(PrefService* pref_service);
-  virtual ~TetherHostResponseRecorder();
-
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
 
   // Records a TetherAvailabilityResponse. This function should be called each
   // time that a response is received from a potential host, even if a
@@ -69,18 +60,12 @@
   virtual std::vector<std::string> GetPreviouslyConnectedHostIds() const;
 
  private:
-  friend class HostScanCacheTest;
-
-  void NotifyObserversPreviouslyConnectedHostIdsChanged();
-
-  // Returns whether the list was changed due to adding the response.
-  bool AddRecentResponse(const std::string& device_id,
+  void AddRecentResponse(const std::string& device_id,
                          const std::string& pref_name);
   std::vector<std::string> GetDeviceIdsForPref(
       const std::string& pref_name) const;
 
   PrefService* pref_service_;
-  base::ObserverList<Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TetherHostResponseRecorder);
 };