Add the Vulkan loader as an optional dependency and use it on Mac
On macOS we can't rely on having the Vulkan loader installed in the
system. So we add the Vulkan loader as an optional dependency of Dawn
and use it on macOS when building Dawn in standalone with Vulkan
support.
Usage of building our own loader might broaden if the loader gains
features that are useful on other OSes. For example the ability to pass
in the "root ICD" entrypoint to the loader so we can have both
Swiftshader and the system driver at the same time.
Bug: dawn:388
Change-Id: I7ade4961cce0463c66846ad17aebf95224f1afcc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/19723
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/build_overrides/vulkan_loader.gni b/build_overrides/vulkan_loader.gni
new file mode 100644
index 0000000..c38074f
--- /dev/null
+++ b/build_overrides/vulkan_loader.gni
@@ -0,0 +1,18 @@
+# Copyright 2020 The Dawn 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.
+
+vulkan_headers_dir = "//third_party/vulkan-headers"
+
+vulkan_gen_subdir = "vulkan_loader"
+vulkan_loader_shared = true
