[Payments] Move JourneyLogger unit tests from Java to C++.

components/payments/core/BUILD.gn

Index: components/payments/core/BUILD.gn
diff --git a/components/payments/core/BUILD.gn b/components/payments/core/BUILD.gn
index 6b8cbc44e575cbad9f9519661f5e49ef37da0661..c0f3850d87d1ec1f764c74ebc755dd5cf5e5efd5 100644
--- a/components/payments/core/BUILD.gn
+++ b/components/payments/core/BUILD.gn
@@ -47,6 +47,7 @@ source_set("unit_tests") {
     "address_normalizer_unittest.cc",
     "basic_card_response_unittest.cc",
     "currency_formatter_unittest.cc",
+    "journey_logger_unittest.cc",
     "payment_address_unittest.cc",
     "payment_method_data_unittest.cc",
     "payment_request_data_util_unittest.cc",
@@ -58,6 +59,7 @@ source_set("unit_tests") {
     "//base/test:test_support",
     "//components/autofill/core/browser",
     "//components/autofill/core/browser:test_support",
+    "//testing/gmock",
     "//testing/gtest",
     "//third_party/libaddressinput:test_support",
   ]