Add GitHub workflow for building Skia on Android and macOS

.github/workflows/build_skia.yml

@@ -0,0 +1,49 @@
+name: Build Skia for Android and macOS
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  # build-android:
+  #   name: Build Skia for Android
+  #   runs-on: ubuntu-latest
+  #   steps:
+  #     - uses: actions/checkout@v2
+  #     - name: Set up Bazel
+  #       uses: bazelbuild/setup-bazelisk@v1
+  #     - name: Build Skia for Android
+  #       run: bazel build //:skia_public --config=android_arm64 --toolchain=//:ndk_linux_arm64_toolchain_config
+
+  build-macos:
+    name: Build Skia for macOS
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+      - name: Set up deptool
+        run: |
+          git config --global init.defaultBranch main
+          git clone 'https://chromium.googlesource.com/chromium/tools/depot_tools.git'
+          export PATH=${PWD}/depot_tools:${PATH}
+          python3 tools/git-sync-deps
+          bin/fetch-ninja
+          export BUILD_ARGS=\
+            target_cpu=\"arm64\" \
+            is_official_build=true \
+            is_debug=false \
+            skia_use_libwebp_decode=true \
+            skia_use_libwebp_encode=true \
+            skia_use_libwebp=false \
+            skia_use_system_libjpeg_turbo=false \
+            skia_use_system_libpng=false \
+            skia_use_system_libwebp=false
+          bin/gn gen out/release-darwin-arm64 --args="$BUILD_ARGS"
+          bin/gn args out/release-darwin-arm64 --list
+          ninja -C out/release-darwin-arm64
+          ls -lh out/release-darwin-arm64