Create common utility class for fuzzing

This moves the usage of Tint in the fuzzers into a single class. This
will be expanded in the future to support emitting shaders, so fuzzing
tests, just need to indicate which reader & writer they want to use,
instead of having each test implement all of the API usage logic
directly.

BUG=tint:199

Change-Id: Id081a374014b7640a07b267e544ddeba3e6329dd
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/36760
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Auto-Submit: Ryan Harrison <rharrison@chromium.org>

fuzzers/tint_common_fuzzer.h

@@ -0,0 +1,39 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef FUZZERS_TINT_COMMON_FUZZER_H_
+#define FUZZERS_TINT_COMMON_FUZZER_H_
+
+#include "include/tint/tint.h"
+
+namespace tint {
+namespace fuzzers {
+
+enum class InputFormat { kWGSL, kSpv, kNone };
+
+class CommonFuzzer {
+ public:
+  explicit CommonFuzzer(InputFormat input);
+  ~CommonFuzzer();
+
+  int Run(const uint8_t* data, size_t size);
+
+ private:
+  InputFormat input_;
+};
+
+}  // namespace fuzzers
+}  // namespace tint
+
+#endif  // FUZZERS_TINT_COMMON_FUZZER_H_