Add WASM target in gn (flutter#31670)

Author: Harry Terkelsen

BUILD.gn

@@ -31,6 +31,14 @@ config("export_dynamic_symbols") {
   }
 }
 
+# Flutter SDK artifacts should only be built when either doing host builds, or
+# for cross-compiled desktop targets.
+# TODO: We can't build the engine artifacts for arm (32-bit) right now;
+# see https://github.com/flutter/flutter/issues/74322
+_build_engine_artifacts =
+    current_toolchain == host_toolchain ||
+    (is_linux && !is_chromeos && current_cpu != "arm") || is_mac
+
 if (flutter_prebuilt_dart_sdk) {
   copy_trees("_copy_trees") {
     sources = [
@@ -45,14 +53,6 @@ if (flutter_prebuilt_dart_sdk) {
   }
 }
 
-# Flutter SDK artifacts should only be built when either doing host builds, or
-# for cross-compiled desktop targets.
-# TODO: We can't build the engine artifacts for arm (32-bit) right now;
-# see https://github.com/flutter/flutter/issues/74322
-_build_engine_artifacts =
-    current_toolchain == host_toolchain ||
-    (is_linux && !is_chromeos && current_cpu != "arm") || is_mac
-
 group("dart_sdk") {
   if (build_engine_artifacts) {
     if (flutter_prebuilt_dart_sdk) {

DEPS

@@ -33,6 +33,12 @@ vars = {
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.
   'canvaskit_cipd_instance': '8MSYGWVWzrTJIoVL00ZquruZs-weuwLBy1kt1AawJiIC',
 
+  # Do not download the Emscripten SDK by default.
+  # This prevents us from downloading the Emscripten toolchain for builds
+  # which do not build for the web. This toolchain is needed to build CanvasKit
+  # for the web engine.
+  'download_emsdk': False,
+
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the
   # Dart SDK's DEPS file for that revision of Dart. The DEPS file for
@@ -155,7 +161,7 @@ deps = {
    # Chromium-style dependencies.
 
   'src/third_party/icu':
-   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '2e0f2989441ec2f55abec30f48e89981dbac2c34',
+   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '1fa4e3959ec6637182b7318ac1d382799454806d',
 
   'src/third_party/khronos':
    Var('chromium_git') + '/chromium/src/third_party/khronos.git' + '@' + '7122230e90547962e0f0c627f62eeed3c701f275',
@@ -565,6 +571,11 @@ deps = {
     'dep_type': 'cipd',
   },
 
+  'src/buildtools/emsdk': {
+   'url': Var('skia_git') + '/external/github.com/emscripten-core/emsdk.git' + '@' + 'fc645b7626ebf86530dbd82fbece74d457e7ae07',
+   'condition': 'download_emsdk',
+  },
+
   # Clang on mac and linux are expected to typically be the same revision.
   # They are separated out so that the autoroller can more easily manage them.
   'src/buildtools/mac-x64/clang': {
@@ -739,6 +750,15 @@ hooks = [
       Var('fuchsia_sdk_path'),
     ]
   },
+  {
+    'name': 'Activate Emscripten SDK',
+    'pattern': '.',
+    'condition': 'download_emsdk',
+    'action': [
+      'python3',
+      'src/flutter/tools/activate_emsdk.py',
+    ]
+  },
   {
     'name': 'Setup githooks',
     'pattern': '.',

ci/licenses_golden/licenses_skia

@@ -651,8 +651,17 @@ FILE: ../../../third_party/skia/BUILD.bazel
 FILE: ../../../third_party/skia/CQ_COMMITTERS
 FILE: ../../../third_party/skia/DEPS
 FILE: ../../../third_party/skia/DIR_METADATA
-FILE: ../../../third_party/skia/OWNERS.android
 FILE: ../../../third_party/skia/WORKSPACE.bazel
+FILE: ../../../third_party/skia/animations/checkbox.xml
+FILE: ../../../third_party/skia/animations/chest#1.jpg
+FILE: ../../../third_party/skia/animations/fire#1.jpg
+FILE: ../../../third_party/skia/animations/images#1.xml
+FILE: ../../../third_party/skia/animations/jet#1.jpg
+FILE: ../../../third_party/skia/animations/lines#1.xml
+FILE: ../../../third_party/skia/animations/movie#1.xml
+FILE: ../../../third_party/skia/animations/paths#1.xml
+FILE: ../../../third_party/skia/animations/redcross#1.jpg
+FILE: ../../../third_party/skia/animations/text#1.xml
 FILE: ../../../third_party/skia/bazel/BUILD.bazel
 FILE: ../../../third_party/skia/bazel/cc_binary_with_flags.bzl
 FILE: ../../../third_party/skia/bazel/common_config_settings/BUILD.bazel
@@ -754,6 +763,16 @@ FILE: ../../../third_party/skia/experimental/tskit/package.json
 FILE: ../../../third_party/skia/experimental/tskit/tsconfig.json
 FILE: ../../../third_party/skia/experimental/wasm-hello-world/BUILD.bazel
 FILE: ../../../third_party/skia/experimental/wasm-hello-world/hello_world.html
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/cpu.js
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/debugger/anim.mskp
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/debugger/index.html
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/debugger/sample.skp
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/externs.js
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/fonts/NotoMono-Regular.ttf
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/gpu.js
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/helper.js
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/karma.conf.js
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/package.json
 FILE: ../../../third_party/skia/experimental/webgpu-bazel/example/index.html
 FILE: ../../../third_party/skia/experimental/webgpu-bazel/src/BUILD
 FILE: ../../../third_party/skia/gm/BUILD.bazel
@@ -784,7 +803,6 @@ FILE: ../../../third_party/skia/include/private/BUILD.bazel
 FILE: ../../../third_party/skia/include/private/chromium/BUILD.bazel
 FILE: ../../../third_party/skia/include/sksl/BUILD.bazel
 FILE: ../../../third_party/skia/include/svg/BUILD.bazel
-FILE: ../../../third_party/skia/include/third_party/BUILD.bazel
 FILE: ../../../third_party/skia/include/utils/BUILD.bazel
 FILE: ../../../third_party/skia/include/utils/mac/BUILD.bazel
 FILE: ../../../third_party/skia/infra/bots/BUILD.bazel
@@ -1893,6 +1911,7 @@ FILE: ../../../third_party/skia/bench/StreamBench.cpp
 FILE: ../../../third_party/skia/bench/SwizzleBench.cpp
 FILE: ../../../third_party/skia/bench/TileImageFilterBench.cpp
 FILE: ../../../third_party/skia/bench/VertexColorSpaceBench.cpp
+FILE: ../../../third_party/skia/experimental/xps_to_png/xps_to_png.cs
 FILE: ../../../third_party/skia/fuzz/Fuzz.cpp
 FILE: ../../../third_party/skia/fuzz/Fuzz.h
 FILE: ../../../third_party/skia/fuzz/FuzzGradients.cpp
@@ -3247,7 +3266,7 @@ FILE: ../../../third_party/skia/src/effects/imagefilters/SkComposeImageFilter.cp
 FILE: ../../../third_party/skia/src/effects/imagefilters/SkDisplacementMapImageFilter.cpp
 FILE: ../../../third_party/skia/src/effects/imagefilters/SkDropShadowImageFilter.cpp
 FILE: ../../../third_party/skia/src/effects/imagefilters/SkTileImageFilter.cpp
-FILE: ../../../third_party/skia/src/gpu/Blend.h
+FILE: ../../../third_party/skia/src/gpu/GrBlend.h
 FILE: ../../../third_party/skia/src/gpu/GrCaps.h
 FILE: ../../../third_party/skia/src/gpu/GrGeometryProcessor.h
 FILE: ../../../third_party/skia/src/gpu/GrPaint.cpp
@@ -3326,6 +3345,7 @@ TYPE: LicenseType.bsd
 FILE: ../../../third_party/skia/bench/BulkRectBench.cpp
 FILE: ../../../third_party/skia/bench/DDLRecorderBench.cpp
 FILE: ../../../third_party/skia/bench/SkSLBench.cpp
+FILE: ../../../third_party/skia/experimental/wasm-skp-debugger/debugger_bindings.cpp
 FILE: ../../../third_party/skia/gm/asyncrescaleandread.cpp
 FILE: ../../../third_party/skia/gm/crbug_908646.cpp
 FILE: ../../../third_party/skia/gm/crbug_946965.cpp
@@ -3445,6 +3465,7 @@ FILE: ../../../third_party/skia/bench/PathOpsBench.cpp
 FILE: ../../../third_party/skia/bench/PolyUtilsBench.cpp
 FILE: ../../../third_party/skia/bench/ShaderMaskFilterBench.cpp
 FILE: ../../../third_party/skia/bench/TypefaceBench.cpp
+FILE: ../../../third_party/skia/experimental/pvg/draw_msg.proto
 FILE: ../../../third_party/skia/fuzz/FuzzCommon.cpp
 FILE: ../../../third_party/skia/fuzz/FuzzPathMeasure.cpp
 FILE: ../../../third_party/skia/fuzz/FuzzRegionOp.cpp
@@ -4182,6 +4203,21 @@ TYPE: LicenseType.bsd
 FILE: ../../../third_party/skia/bench/FindCubicConvex180ChopsBench.cpp
 FILE: ../../../third_party/skia/bench/GlyphQuadFillBench.cpp
 FILE: ../../../third_party/skia/bench/TessellateBench.cpp
+FILE: ../../../third_party/skia/experimental/skrive/include/SkRive.h
+FILE: ../../../third_party/skia/experimental/skrive/src/Artboard.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Color.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Component.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Drawable.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Ellipse.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Node.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Paint.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Rectangle.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/Shape.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/SkRive.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/reader/BinaryReader.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/reader/JsonReader.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/reader/StreamReader.cpp
+FILE: ../../../third_party/skia/experimental/skrive/src/reader/StreamReader.h
 FILE: ../../../third_party/skia/fuzz/FuzzSkParagraph.cpp
 FILE: ../../../third_party/skia/gm/3d.cpp
 FILE: ../../../third_party/skia/gm/bc1_transparency.cpp
@@ -6091,8 +6127,6 @@ FILE: ../../../third_party/skia/experimental/graphite/src/UploadTask.h
 FILE: ../../../third_party/skia/experimental/graphite/src/mtl/MtlSampler.h
 FILE: ../../../third_party/skia/experimental/graphite/src/mtl/MtlSampler.mm
 FILE: ../../../third_party/skia/gm/bug12866.cpp
-FILE: ../../../third_party/skia/include/core/SkAlphaType.h
-FILE: ../../../third_party/skia/include/core/SkColorType.h
 FILE: ../../../third_party/skia/include/private/SkUniquePaintParamsID.h
 FILE: ../../../third_party/skia/src/core/SkBuiltInCodeSnippetID.h
 FILE: ../../../third_party/skia/src/core/SkDebugUtils.h
@@ -6102,8 +6136,6 @@ FILE: ../../../third_party/skia/src/core/SkKeyHelpers.cpp
 FILE: ../../../third_party/skia/src/core/SkKeyHelpers.h
 FILE: ../../../third_party/skia/src/core/SkPaintParamsKey.cpp
 FILE: ../../../third_party/skia/src/core/SkPaintParamsKey.h
-FILE: ../../../third_party/skia/src/core/SkPipelineData.cpp
-FILE: ../../../third_party/skia/src/core/SkPipelineData.h
 FILE: ../../../third_party/skia/src/core/SkSLTypeShared.h
 FILE: ../../../third_party/skia/src/core/SkShaderCodeDictionary.cpp
 FILE: ../../../third_party/skia/src/core/SkShaderCodeDictionary.h
@@ -6181,6 +6213,7 @@ FILE: ../../../third_party/skia/src/gpu/ops/PathStencilCoverOp.h
 FILE: ../../../third_party/skia/src/gpu/ops/PathTessellateOp.cpp
 FILE: ../../../third_party/skia/src/gpu/ops/PathTessellateOp.h
 FILE: ../../../third_party/skia/src/gpu/tessellate/AffineMatrix.h
+FILE: ../../../third_party/skia/src/gpu/tessellate/PatchWriter.cpp
 FILE: ../../../third_party/skia/src/gpu/tessellate/PatchWriter.h
 FILE: ../../../third_party/skia/src/gpu/tessellate/PathCurveTessellator.cpp
 FILE: ../../../third_party/skia/src/gpu/tessellate/PathCurveTessellator.h

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 80ac7a3b149c4cac0af4058b3b4a4bb6
+Signature: 63800bcd154af7272865369dc774c2c4
 
 UNUSED LICENSES:
 
@@ -18098,6 +18098,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -18227,6 +18228,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -18366,6 +18368,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -18500,6 +18503,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -18633,6 +18637,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -18771,6 +18776,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -18905,6 +18911,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -19038,6 +19045,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -19144,6 +19152,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch
@@ -19317,6 +19326,7 @@ FILE: ../../../third_party/icu/android_small/icudtl_extra.dat
 FILE: ../../../third_party/icu/cast/brkitr.patch
 FILE: ../../../third_party/icu/cast/icudtl.dat
 FILE: ../../../third_party/icu/chromeos/icudtl.dat
+FILE: ../../../third_party/icu/chromeos/icudtl.dat.hash
 FILE: ../../../third_party/icu/common/icudtb.dat
 FILE: ../../../third_party/icu/common/icudtl.dat
 FILE: ../../../third_party/icu/flutter/brkitr.patch

ci/licenses_golden/tool_signature

@@ -1,2 +1,2 @@
-Signature: 270842a9eb9687ced20abdf5f131bafd
+Signature: 5efe7843d99ba138e2bb7dac2441b5b8
 

lib/web_ui/BUILD.gn

@@ -0,0 +1,7 @@
+# Copyright 2022 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+group("canvaskit") {
+  deps = [ "//third_party/skia/modules/canvaskit" ]
+}

lib/web_ui/README.md

@@ -265,6 +265,59 @@ environment variable:
 FELT_USE_SNAPSHOT=false felt <command>
 ```
 
+## Building CanvasKit
+
+To build CanvasKit locally, you must first set up your gclient config to
+activate the Emscripten SDK, which is the toolchain used to build CanvasKit.
+To do this, replace the contents of your .gclient file at the root of the
+project (i.e. in the parent directory of the `src` directory) with:
+
+```
+solutions = [
+  {
+    "managed": False,
+    "name": "src/flutter",
+    "url": "[email protected]:<your_username_here>/engine.git",
+    "custom_deps": {},
+    "deps_file": "DEPS",
+    "safesync_url": "",
+    "custom_vars": {
+      "download_emsdk": True,
+    },
+  },
+]
+```
+
+Now run `gclient sync` and it should pull in the Emscripten SDK and activate it.
+
+To build CanvasKit with `felt`, run:
+
+```
+felt build --build-canvaskit
+```
+
+This will build CanvasKit in `out/wasm_debug`. If you now run
+
+```
+felt test
+```
+
+it will detect that you have built CanvasKit and use that instead of the one
+from CIPD to run the tests against.
+
+### Upgrading the Emscripten SDK for the CanvasKit build
+
+The version of the Emscripten SDK should be kept up to date with the version
+used in the Skia build. That version can be found in
+`third_party/skia/bin/activate-emsdk`. It will probably also be necessary to
+roll the dependency on `third_party/emsdk` in DEPS to the same version as in
+`third_party/skia/DEPS`.
+
+Once you know the version for the Emscripten SDK, change the line in
+`tools/activate_emsdk.py` which defines `EMSDK_VERSION` to match Skia.
+
+
+
 [1]: https://github.com/flutter/flutter/wiki/Setting-up-the-Engine-development-environment
 [2]: https://github.com/flutter/engine/blob/main/lib/web_ui/dev/browser_lock.yaml
 [4]: https://chrome-infra-packages.appspot.com/p/flutter_internal