[CrOS Tether] Fix a buffer overflow issue caught by the ASAN bots.

chromeos/components/tether/ble_scanner.cc

Index: chromeos/components/tether/ble_scanner.cc
diff --git a/chromeos/components/tether/ble_scanner.cc b/chromeos/components/tether/ble_scanner.cc
index 5ed761d731f36c666f7f003c9d16dd78ba10e20e..709e5f5c30a2904924b53534e8fc7d57f9d08a1d 100644
--- a/chromeos/components/tether/ble_scanner.cc
+++ b/chromeos/components/tether/ble_scanner.cc
@@ -228,7 +228,7 @@ void BleScanner::HandleDeviceUpdated(
   std::string service_data_str;
   char* string_contents_ptr =
       base::WriteInto(&service_data_str, service_data->size() + 1);
-  memcpy(string_contents_ptr, service_data->data(), service_data->size() + 1);
+  memcpy(string_contents_ptr, service_data->data(), service_data->size());
 
   CheckForMatchingScanFilters(bluetooth_device, service_data_str);
 }