[Web Payment] Requested method data filter.

This patch adds a utility function (and corresponding unit test) for
filtering the requested payment method data according to the payment
method names supported by an app. This prevents a payment app from
receiving method-specific information about methods that it does not
support.

Bug: 1061503
Change-Id: I901a2fd6166ddc031f8910816a0e3f8fdc5a7b93
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2300344
Commit-Queue: Rouslan Solomakhin <rouslan@chromium.org>
Reviewed-by: Danyao Wang <danyao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798465}

components/payments/core/payment_request_data_util.cc

@@ -166,5 +166,17 @@ base::string16 FormatCardNumberForDisplay(const base::string16& card_number) {
   return number;
 }
 
+std::map<std::string, std::set<std::string>> FilterStringifiedMethodData(
+    const std::map<std::string, std::set<std::string>>& stringified_method_data,
+    const std::set<std::string>& supported_payment_method_names) {
+  std::map<std::string, std::set<std::string>> result;
+  for (const auto& pair : stringified_method_data) {
+    if (base::Contains(supported_payment_method_names, pair.first)) {
+      result[pair.first] = pair.second;
+    }
+  }
+  return result;
+}
+
 }  // namespace data_util
 }  // namespace payments

components/payments/core/payment_request_data_util.h

@@ -64,6 +64,23 @@ void ParseSupportedMethods(
 // numbers, which start with a letter.
 base::string16 FormatCardNumberForDisplay(const base::string16& card_number);
 
+// Returns the subset of |stringified_method_data| map where the keys are in the
+// |supported_payment_method_names| set. Used for ensuring that a payment app
+// will not be queried about payment method names that it does not support.
+//
+// FilterStringifiedMethodData({"a": {"b"}: "c": {"d"}}, {"a"}) -> {"a": {"b"}}
+//
+// Both the return value and the first parameter to the function have the
+// following format:
+// Key: Payment method identifier, such as "example-test" or
+//      "https://example.test".
+// Value: The set of all payment method specific parameters for the given
+//        payment method identifier, each one serialized into a JSON string,
+//        e.g., '{"key": "value"}'.
+std::map<std::string, std::set<std::string>> FilterStringifiedMethodData(
+    const std::map<std::string, std::set<std::string>>& stringified_method_data,
+    const std::set<std::string>& supported_payment_method_names);
+
 }  // namespace data_util
 }  // namespace payments
 

components/payments/core/payment_request_data_util_unittest.cc

@@ -4,7 +4,10 @@
 
 #include "components/payments/core/payment_request_data_util.h"
 
+#include <map>
 #include <memory>
+#include <set>
+#include <string>
 
 #include "base/json/json_writer.h"
 #include "base/macros.h"
@@ -274,5 +277,25 @@ TEST(PaymentRequestDataUtil, ParseSupportedMethods_MultipleEntries) {
               UnorderedElementsAre(kBasicCardMethodName, kBobPayMethod));
 }
 
+TEST(PaymentRequestDataUtil, FilterStringifiedMethodData) {
+  std::map<std::string, std::set<std::string>> requested;
+  std::set<std::string> supported;
+  EXPECT_TRUE(FilterStringifiedMethodData(requested, supported).empty());
+
+  requested["a"].insert("{\"b\": \"c\"}");
+  EXPECT_TRUE(FilterStringifiedMethodData(requested, supported).empty());
+
+  requested["x"].insert("{\"y\": \"z\"}");
+  EXPECT_TRUE(FilterStringifiedMethodData(requested, supported).empty());
+
+  supported.insert("x");
+  std::map<std::string, std::set<std::string>> expected;
+  expected["x"].insert("{\"y\": \"z\"}");
+  EXPECT_EQ(expected, FilterStringifiedMethodData(requested, supported));
+
+  supported.insert("g");
+  EXPECT_EQ(expected, FilterStringifiedMethodData(requested, supported));
+}
+
 }  // namespace data_util
 }  // namespace payments