Add onGetUsbPrinterInfoRequested event to printerProvider API.

chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc

Index: chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
diff --git a/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc b/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
index 1f701a6067c5e30f63824dfd9903e15a018636e1..00f1319707a950e58d33181653fa656f2bddd164 100644
--- a/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
+++ b/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
@@ -297,6 +297,13 @@ class FakePrinterProviderAPI : public PrinterProviderAPI {
     pending_print_requests_.push_back(request_info);
   }
 
+  void DispatchGetUsbPrinterInfoRequested(
+      const std::string& extension_id,
+      scoped_refptr<device::UsbDevice> device,
+      const PrinterProviderAPI::GetPrinterInfoCallback& callback) override {
+    ADD_FAILURE() << "Not reached.";
+  }
+
   size_t pending_get_printers_count() const {
     return pending_printers_callbacks_.size();
   }