Remove base::Hash() usage in fuzzers.

base::Hash() is deprecated and is being replaced by base::FastHash().
The output of base::FastHash() is only fixed within the lifetime of a
single process, so if the code depends on the mapping of inputs to hash
outputs not changing over time, base::PersistentHash() must be used
instead.

Bug: 1025358
Change-Id: I88f09613aa5b099517de6079f857fbf0f6d1d50f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954453Reviewed-by: Oliver Chang <ochang@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738247}

media/base/bit_reader_fuzzertest.cc

@@ -5,19 +5,29 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "base/hash/hash.h"
+#include "base/containers/buffer_iterator.h"
+#include "base/containers/span.h"
 #include "base/numerics/safe_conversions.h"
 #include "media/base/bit_reader.h"
 #include "media/base/test_random.h"
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  media::BitReader reader(data, base::checked_cast<int>(size));
+  base::BufferIterator<const uint8_t> iterator(data, size);
+
+  const uint32_t* random_seed = iterator.Object<uint32_t>();
+  if (!random_seed)
+    return 0;
 
   // Need a simple random number generator to generate the number of bits to
-  // read/skip in a reproducible way (given the same |data|). Using Hash() to
-  // ensure the seed varies significantly over minor changes in |data|.
-  media::TestRandom rnd(base::Hash(data, size));
+  // read/skip in a reproducible way (given the same |data|).
+  media::TestRandom rnd(*random_seed);
+
+  base::span<const uint8_t> remaining =
+      iterator.Span<uint8_t>(iterator.total_size() - iterator.position());
+
+  media::BitReader reader(remaining.data(),
+                          base::checked_cast<int>(remaining.size()));
 
   // Read and skip through the data in |reader|.
   while (reader.bits_available() > 0) {

testing/libfuzzer/fuzzers/hash_fuzzer.cc

@@ -5,10 +5,12 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "base/containers/span.h"
 #include "base/hash/hash.h"
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  base::Hash(data, size);
+  base::PersistentHash(base::make_span(data, size));
+  base::FastHash(base::make_span(data, size));
   return 0;
 }