Add some policy integration tests

Cherry-pick from branch rvc-dev of http://go/wvgerrit/105824 and
rvc-widevine-release http://go/ag/12561660

This adds two policy integration tests to verify that we are handling offline
licenses correctly.

Bug: 161023174
Bug: 129301787
Test: WV unit/integration tests
Change-Id: I20f5d6a9fbfd2ff8cff361e1005e45b46c700704

libwvdrmengine/cdm/core/test/test_base.h

@@ -76,6 +76,27 @@ class WvCdmTestBase : public ::testing::Test {
   bool binary_provisioning_;
 };
 
+// This just makes the constructor public so that we can create one with dummy
+// metrics and file system.
+class TestCdmEngine : public CdmEngine {
+ public:
+  TestCdmEngine(FileSystem* file_system,
+                std::shared_ptr<metrics::EngineMetrics> metrics)
+      : CdmEngine(file_system, metrics) {}
+};
+
+class WvCdmTestBaseWithEngine : public WvCdmTestBase {
+ public:
+  WvCdmTestBaseWithEngine()
+      : dummy_engine_metrics_(new metrics::EngineMetrics()),
+        cdm_engine_(&file_system_, dummy_engine_metrics_) {}
+
+ protected:
+  FileSystem file_system_;
+  shared_ptr<metrics::EngineMetrics> dummy_engine_metrics_;
+  TestCdmEngine cdm_engine_;
+};
+
 class TestCryptoSession : public CryptoSession {
  public:
   explicit TestCryptoSession(metrics::CryptoMetrics* crypto_metrics);