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_copy_buffer_fuzz.cc

@@ -7,31 +7,39 @@
 #include "oemcrypto_fuzz_helper.h"
 #include "oemcrypto_fuzz_structs.h"
 
-namespace wvoec {
+namespace {
+
+// Avoid calling non-trivial destructor.
+wvoec::OEMCryptoLicenseAPIFuzz& license_api_fuzz =
+    *new wvoec::OEMCryptoLicenseAPIFuzz;
+
+}  // namespace
+
+extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv) {
+  wvoec::RedirectStdoutToFile();
+  license_api_fuzz.Initialize();
+  return 0;
+}
 
 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();
-
   // OEMCrypto_DestBufferDesc and a buffer from which data needs to be copied
   // are expected as inputs to copy buffer API.
   // Input fuzzed data is interpreted as:
   // (OEMCrypto_DestBufferDesc | subsample_flags | input_buffer)
-  OEMCrypto_Copy_Buffer_Fuzz fuzzed_structure;
+  wvoec::OEMCrypto_Copy_Buffer_Fuzz fuzzed_structure;
   if (size < sizeof(fuzzed_structure)) {
     return 0;
   }
   FuzzedDataProvider fuzzed_data(data, size);
   fuzzed_data.ConsumeData(&fuzzed_structure, sizeof(fuzzed_structure));
-  ConvertDataToValidEnum(OEMCrypto_BufferType_MaxValue,
-                         &fuzzed_structure.dest_buffer_desc.type);
-  fuzzed_structure.dest_buffer_desc.buffer_config %= MAX_FUZZ_OUTPUT_LENGTH + 1;
+  wvoec::ConvertDataToValidEnum(OEMCrypto_BufferType_MaxValue,
+                                &fuzzed_structure.dest_buffer_desc.type);
+  fuzzed_structure.dest_buffer_desc.buffer_config %=
+      wvoec::MAX_FUZZ_OUTPUT_LENGTH + 1;
   const std::vector<OEMCrypto_SharedMemory> input_buffer =
       fuzzed_data.ConsumeRemainingBytes<OEMCrypto_SharedMemory>();
 
-  OEMCryptoLicenseAPIFuzz license_api_fuzz;
-  const uint32_t session_id = license_api_fuzz.session()->session_id();
+  const uint32_t session_id = license_api_fuzz.session().session_id();
 
   // Initialize output buffer.
   OEMCrypto_DestBufferDesc dest_buffer_desc;
@@ -79,5 +87,3 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   return 0;
 }
-
-}  // namespace wvoec