actions_parser_fuzzer: Cap input size

Change the content_input_actions_parser_fuzzer to ignore huge
inputs, in order to avoid spurious timeout and OOM clusterfuzz
reports.

The exact constant is chosen semi-arbitrarily: we set it at 100 KB;
for reference, the OOM report happened on a 686 KB input.

Fixed: 1497681
Change-Id: Ic501be24c60a8a27f2b4d0317fe73913f80c673f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5057760
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Auto-Submit: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1228816}

content/common/input/actions_parser_fuzzer.cc

@@ -14,6 +14,12 @@
 #include "third_party/abseil-cpp/absl/types/optional.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  constexpr size_t kMaxInputSize = 100 * 1000;
+  if (size > kMaxInputSize) {
+    // To avoid spurious timeout and out-of-memory fuzz reports.
+    return 0;
+  }
+
   absl::optional<base::Value> value = base::JSONReader::Read(
       base::StringPiece(reinterpret_cast<const char*>(data), size));
   if (!value)