BUILD.gn: Move last third_party deps to third_party/BUILD.gn

scripts/dawn_features.gni

@@ -0,0 +1,35 @@
+# Copyright 2018 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.
+
+declare_args() {
+  # Enable Dawn's ASSERTs even in release builds
+  dawn_always_assert = false
+
+  # Enables the compilation of Dawn's D3D12 backend
+  dawn_enable_d3d12 = is_win
+
+  # Enables the compilation of Dawn's Metal backend
+  dawn_enable_metal = is_mac
+
+  # Enables the compilation of Dawn's Null backend
+  # (required for unittests, obviously non-conformant)
+  dawn_enable_null = true
+
+  # Enables the compilation of Dawn's OpenGL backend
+  # (best effort, non-conformant)
+  dawn_enable_opengl = is_linux
+
+  # Enables the compilation of Dawn's Vulkan backend
+  dawn_enable_vulkan = is_linux || is_win
+}