Avoid creating a storage folder for fastboot devices command

Bug: 284267164
Bug: 284786311
Test: fastboot devices doesn't create a .fastboot folder
Change-Id: I3e44c2a838e4287e6220c18f6e805cc71e0c9669
Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
diff --git a/fastboot/storage.h b/fastboot/storage.h
index 0cc3d86..ae9d846 100644
--- a/fastboot/storage.h
+++ b/fastboot/storage.h
@@ -24,13 +24,15 @@
 class ConnectedDevicesStorage {
   public:
     ConnectedDevicesStorage();
+
+    bool Exists() const;
     void WriteDevices(const FileLock&, const std::set<std::string>& devices);
     std::set<std::string> ReadDevices(const FileLock&);
     void Clear(const FileLock&);
-
     FileLock Lock() const;
 
   private:
+    std::string home_fastboot_path_;
     std::string devices_path_;
     std::string devices_lock_path_;
 };
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