fastboot: get rid of manual transport memory management

Existing code has transport memory leaks. Use smart pointers
for transport to get rid of those cases and manual memory
management

Test: atest fastboot_test
Test: manually checked transport isn't leaking anymore
Bug: 296629925
Change-Id: Ifdf162d5084f61ae5c1d2b56a897464af58100da
Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
diff --git a/fastboot/usb_windows.cpp b/fastboot/usb_windows.cpp
index 67bf8a3..56a6e7d 100644
--- a/fastboot/usb_windows.cpp
+++ b/fastboot/usb_windows.cpp
@@ -381,7 +381,13 @@
     return handle;
 }
 
-UsbTransport* usb_open(ifc_match_func callback, uint32_t) {
+std::unique_ptr<UsbTransport> usb_open(ifc_match_func callback, uint32_t) {
+    std::unique_ptr<UsbTransport> result;
     std::unique_ptr<usb_handle> handle = find_usb_device(callback);
-    return handle ? new WindowsUsbTransport(std::move(handle)) : nullptr;
+
+    if (handle) {
+        result = std::make_unique<WindowsUsbTransport>(std::move(handle));
+    }
+
+    return result;
 }