Code Drop Two (Update One)

This is the second code drop for the white-box api reference
implementation and tests. This corrects the errors in the license
white-box reference implementation and implements the remaining
test cases.

It should be noted that there is one test case missing, the test case
for handling ChromeOS's unique policy settings.

In order to make the tests easier to create and read, a license
builder class was created and golden content and keys were wrapped in
their own classes.

How key errors are communicated was changed in the API.
WB_RESULT_NO_SUCH_KEY and WB_RESULT_WRONG_KEY_TYPE were merged into
WB_RESULT_KEY_UNAVAILABLE.

api/license_whitebox_test_base.cc

@@ -0,0 +1,36 @@
+// Copyright 2020 Google LLC. All Rights Reserved.
+
+#include "api/license_whitebox_test_base.h"
+
+#include <string>
+
+#include "api/test_data.h"
+
+namespace widevine {
+
+void LicenseWhiteboxTestBase::SetUp() {
+  const std::vector<uint8_t> init_data = GetLicenseInitData();
+  ASSERT_EQ(WB_License_Create(init_data.data(), init_data.size(), &whitebox_),
+            WB_RESULT_OK);
+
+  const auto public_key_data = GetMatchingLicensePublicKey();
+  public_key_.reset(RsaPublicKey::Create(
+      std::string(public_key_data.begin(), public_key_data.end())));
+
+  ASSERT_TRUE(public_key_);
+}
+
+void LicenseWhiteboxTestBase::TearDown() {
+  WB_License_Delete(whitebox_);
+}
+
+void LicenseWhiteboxTestBase::Modify(std::vector<uint8_t>* data) const {
+  ASSERT_TRUE(data);
+  ASSERT_GT(data->size(), 0);
+
+  // Bitwise-not the first byte so that we are guaranteed to have at least one
+  // byte different from the original data.
+  data->data()[0] = ~data->data()[0];
+}
+
+}  // namespace widevine