Clean up fuzz helper classes

- Remove OEMCrypto state changes hidden in constructors and destructors.
- Use composition instead of inheritance to structure classes.
- Avoid calling non-trivial destructors for objects with static
  lifetime.

Merged from https://widevine-internal-review.googlesource.com/168497
Merged from https://widevine-internal-review.googlesource.com/171170
Merged from https://widevine-internal-review.googlesource.com/171171
Merged from https://widevine-internal-review.googlesource.com/171870

Change-Id: I20476a7b1132d11f011b8650ec01e3c2dc3fc0e8

libwvdrmengine/oemcrypto/test/fuzz_tests/oemcrypto_fuzz_helper.cc

@@ -1,9 +1,12 @@
 // Copyright 2020 Google LLC. All Rights Reserved. This file and proprietary
 // source code may only be used and distributed under the Widevine
 // License Agreement.
+
+#include "OEMCryptoCENC.h"
 #include "oemcrypto_fuzz_helper.h"
 
 namespace wvoec {
+
 void RedirectStdoutToFile() { freopen("log.txt", "a", stdout); }
 
 std::vector<FuzzedData> SplitFuzzedData(const uint8_t* data, size_t size) {
@@ -22,6 +25,26 @@ std::vector<FuzzedData> SplitFuzzedData(const uint8_t* data, size_t size) {
   return result;
 }
 
+void InitializeFuzz(SessionUtil& session_util) {
+  wvoec::global_features.Initialize();
+  OEMCrypto_SetSandbox(kTestSandbox, sizeof(kTestSandbox));
+  OEMCrypto_Initialize();
+  OEMCrypto_EnterTestMode();
+  session_util.EnsureTestROT();
+}
+
+void OEMCryptoLicenseAPIFuzz::Initialize() {
+  InitializeFuzz(session_util_);
+  session_.open();
+  session_util_.InstallTestDrmKey(&session_);
+  session_.GenerateNonce();
+}
+
+void OEMCryptoLicenseAPIFuzz::Terminate() {
+  session_.close();
+  OEMCrypto_Terminate();
+}
+
 void OEMCryptoLicenseAPIFuzz::LoadLicense() {
   license_messages_.SignAndVerifyRequest();
   license_messages_.CreateDefaultResponse();
@@ -30,6 +53,18 @@ void OEMCryptoLicenseAPIFuzz::LoadLicense() {
   CheckStatusAndExitFuzzerOnFailure(sts, OEMCrypto_SUCCESS);
 }
 
+void OEMCryptoProvisioningAPIFuzz::Intialize() {
+  InitializeFuzz(session_util_);
+
+  // Opens a session and Generates Nonce.
+  provisioning_messages_.PrepareSession(session_util_.keybox_);
+}
+
+void OEMCryptoProvisioningAPIFuzz::Terminate() {
+  session_.close();
+  OEMCrypto_Terminate();
+}
+
 void OEMCryptoProvisioningAPIFuzz::LoadProvisioning() {
   provisioning_messages_.SignAndVerifyRequest();
   provisioning_messages_.CreateDefaultResponse();
@@ -62,4 +97,5 @@ void CheckStatusAndExitFuzzerOnFailure(OEMCryptoResult result,
     abort();
   }
 }
+
 }  // namespace wvoec