Add support for SPIRV reading to BUILD.gn

BUG=dawn:16

Change-Id: I1da30fed82a310007674801e3b1e853b25d5b573
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/19640
Reviewed-by: dan sinclair <dsinclair@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
diff --git a/tint_overrides_with_defaults.gni b/tint_overrides_with_defaults.gni
new file mode 100644
index 0000000..dc7d731
--- /dev/null
+++ b/tint_overrides_with_defaults.gni
@@ -0,0 +1,61 @@
+# Copyright 2020 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.
+
+import("//build_overrides/tint.gni")
+
+# This file contains Tint-related build flags.
+
+declare_args() {
+  # Path to spirv-tools checkout
+  if (!defined(tint_spirv_tools_dir)) {
+    tint_spirv_tools_dir = "//third_party/spirv-tools"
+  }
+
+  # Path to spirv-tools generated files, relative to |target_gen_dir|
+  if (!defined(tint_spirv_tools_gen)) {
+    tint_spirv_tools_gen = "third_party/spirv-tools"
+  }
+
+  # Path to spirv-headers checkout
+  if (!defined(tint_spirv_headers_dir)) {
+    tint_spirv_headers_dir = "//third_party/spirv-headers"
+  }
+
+  # Generate documentation
+  # TODO(rharrison): Implement documentation support
+  tint_build_doc = false
+
+  # Build the SPIR-V input reader
+  if (!defined(tint_build_spv_reader)) {
+    tint_build_spv_reader = false
+  }
+
+  # TODO(rharrison): Implement support for the reset of the reader/writers
+
+  # Generate fuzzers
+  # TODO(rharrison): Implement fuzzer support
+  tint_build_fuzzers = false
+
+  # Enable memory sanitizer
+  # TODO(rharrison): Implement sanitizer support
+  tint_enable_msan = false
+
+  # Enable address sanitizer
+  # TODO(rharrison): Implement sanitizer support
+  tint_enable_msan = false
+
+  # Enable undefined behaviour sanitizer
+  # TODO(rharrison): Implement sanitizer support
+  tint_enable_ubsan = false
+}