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_decrypt_hash_fuzz.cc

@@ -9,23 +9,21 @@
 #include "OEMCryptoCENC.h"
 #include "oemcrypto_fuzz_helper.h"
 
-using namespace wvoec;
-
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  // Redirect printf and log statements from oemcrypto functions to a file to
-  // reduce noise
-  RedirectStdoutToFile();
+  wvoec::RedirectStdoutToFile();
+
+  wvoec::OEMCryptoLicenseAPIFuzz license_api_fuzz;
+  license_api_fuzz.Initialize();
 
-  OEMCryptoLicenseAPIFuzz license_api_fuzz;
   FuzzedDataProvider fuzzed_data(data, size);
 
   if (fuzzed_data.ConsumeBool()) {
     license_api_fuzz.license_messages().set_control(
         license_api_fuzz.license_messages().control() |
-        kControlAllowHashVerification);
+        wvoec::kControlAllowHashVerification);
   }
 
-  const uint32_t session_id = license_api_fuzz.session()->session_id();
+  const uint32_t session_id = license_api_fuzz.session().session_id();
   const std::array<uint8_t, 16> content_key_id{};
   const uint32_t frame_number = fuzzed_data.ConsumeIntegral<uint32_t>();
   std::array<OEMCrypto_SharedMemory, 1> sample_buffer{};
@@ -62,13 +60,14 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   license_api_fuzz.LoadLicense();
   std::vector<uint8_t> key_handle;
-  GetKeyHandleIntoVector(session_id, content_key_id.data(),
-                         content_key_id.size(), OEMCrypto_CipherMode_CENC,
-                         key_handle);
+  wvoec::GetKeyHandleIntoVector(session_id, content_key_id.data(),
+                                content_key_id.size(),
+                                OEMCrypto_CipherMode_CENC, key_handle);
   OEMCrypto_SetDecryptHash(session_id, frame_number, hash.data(), hash.size());
   OEMCrypto_DecryptCENC(key_handle.data(), key_handle.size(), &sample, 1,
                         &pattern);
   OEMCrypto_GetHashErrorCode(session_id, failed_frame_number);
 
+  license_api_fuzz.Terminate();
   return 0;
 }