Apply Tizen GL-only GN optimization flags

Disable unused Vulkan-related backends and validation layers for Tizen GL engine artifacts generated by the GitHub Actions workflow.

Applied GN args:

- skia_use_vulkan=false
- shell_enable_vulkan=false
- impeller_enable_vulkan=false
- enable_vulkan_validation_layers=false
- impeller_enable_vulkan_validation_layers=false

This configuration is intended for the current Tizen GL Skia and GL Impeller artifacts. The expected benefit is smaller engine/package size and a modest resident-memory reduction, while launch-time improvement is expected to be negligible.

Known limitations and risks:

- Vulkan Impeller artifacts must not reuse this configuration because the Vulkan Impeller backend is not built.
- Vulkan shell/surface and Skia Vulkan paths are unavailable in these artifacts.
- Debug builds cannot use Vulkan validation layers for Vulkan diagnostics.
- GL-only artifacts should be distinguishable from Vulkan-ready artifacts to avoid validation mistakes.
- When Tizen changes the default renderer to Vulkan Impeller, GL and Vulkan artifact configurations should be split.
- Future platform-view, video, external texture, or shared-image paths that depend on Vulkan image import require Vulkan-enabled artifacts.
- The Windows workflow expands TIZEN_GL_GN_ARGS by whitespace, so future quoted or space-containing GN args need explicit handling.

Author: JSUYA

.github/workflows/build.yml

@@ -1,6 +1,15 @@
 name: Build
 
 on: [push, pull_request]
+
+env:
+  TIZEN_GL_GN_ARGS: >-
+    --gn-args=skia_use_vulkan=false
+    --gn-args=shell_enable_vulkan=false
+    --gn-args=impeller_enable_vulkan=false
+    --gn-args=enable_vulkan_validation_layers=false
+    --gn-args=impeller_enable_vulkan_validation_layers=false
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -78,7 +87,8 @@ jobs:
             --runtime-mode ${{ matrix.mode }} \
             --enable-fontconfig \
             --disable-desktop-embeddings \
-            --target-dir build
+            --target-dir build \
+            ${TIZEN_GL_GN_ARGS}
           cd engine/src
           ninja -C out/build flutter_engine_library
           cp -f flutter/third_party/icu/flutter/icudtl.dat out/build
@@ -96,7 +106,8 @@ jobs:
           --runtime-mode ${{ matrix.mode }} \
           --enable-fontconfig \
           --disable-desktop-embeddings \
-          --target-dir build
+          --target-dir build \
+          ${TIZEN_GL_GN_ARGS}
 
           cd engine/src
           ninja -C out/build flutter_engine_library
@@ -197,12 +208,14 @@ jobs:
       - name: Build
         working-directory: C:\workspace\flutter\engine\src
         run: |
+          $tizenGnArgs = $Env:TIZEN_GL_GN_ARGS -split ' '
           python3 .\flutter\tools\gn `
             --linux `
             --linux-cpu=${{ matrix.arch }} `
             --runtime-mode=${{ matrix.mode }} `
             --no-goma `
-            --target-dir build
+            --target-dir build `
+            @tizenGnArgs
           ninja -C .\out\build gen_snapshot
 
       - uses: actions/upload-artifact@v4
@@ -258,7 +271,8 @@ jobs:
             --target-triple _ \
             --runtime-mode=${{ matrix.mode }} \
             --disable-desktop-embeddings \
-            --target-dir build
+            --target-dir build \
+            ${TIZEN_GL_GN_ARGS}
           cd engine/src
           ninja -C out/build clang_arm64/gen_snapshot
 
@@ -315,7 +329,8 @@ jobs:
             --target-triple _ \
             --runtime-mode=${{ matrix.mode }} \
             --disable-desktop-embeddings \
-            --target-dir build
+            --target-dir build \
+            ${TIZEN_GL_GN_ARGS}
           cd engine/src
           ninja -C out/build clang_x64/gen_snapshot