Update Flutter 3.44.4

[JSUYA]

flutter-tizen/flutter-tizen#783

[gemini-code-assist]

Code Review

This pull request introduces Tizen cross-compilation support, including a sysroot generator, Dockerfile, and custom toolchain configurations, alongside adding Vulkan external texture support to the embedder API. However, several critical issues were identified in the review: globally disabling GLES3 shaders and unit tests, as well as simplifying host build detection, will break other platforms and CI. Additionally, replacing default Linux fonts globally breaks standard desktop font fallback. The Vulkan external texture implementation contains potential crashes from missing null checks on command buffers and unhandled zero-sized textures, and discards transparency by using an opaque color type. Finally, the Tizen sysroot generator contains security vulnerabilities from unencrypted HTTP downloads and unsafe shell execution, and the Dockerfile can be optimized by cleaning up the package manager cache.

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engine/src/flutter/impeller/tools/shaders.gni (126-140)

Removing GLES3 shaders globally from impeller_shaders will break Impeller on all other platforms (such as Android) that rely on GLES3 shaders. If GLES3 shaders need to be disabled for Tizen or custom builds, this should be controlled via a conditional GN argument rather than removing them globally.

engine/src/flutter/shell/platform/embedder/embedder_external_texture_vulkan.cc (155-157)

The call to CreateCommandBuffer() can return nullptr if the context is in a bad state or being disposed. Dereferencing it directly via Cast(*buffer) will cause a crash. Add a null check to handle this safely.

    auto buffer = impeller_context.CreateCommandBuffer();
    if (!buffer) {
      return nullptr;
    }
    impeller::CommandBufferVK& buffer_vk =
        impeller::CommandBufferVK::Cast(*buffer);

engine/src/flutter/shell/platform/embedder/embedder_external_texture_vulkan.cc (136-140)

If the embedder returns a FlutterVulkanTexture with width or height set to 0 (which is documented as the default/optional behavior in embedder.h), Impeller will attempt to create a 0x0 texture and fail or crash. Unlike the Skia path, there is no fallback here. Populate the width and height with the fallback size if they are not specified.

  std::unique_ptr<FlutterVulkanTexture> texture_desc =
      external_texture_callback_(texture_id, size.width(), size.height());
  if (!texture_desc) {
    return nullptr;
  }
  if (texture_desc->width == 0 || texture_desc->height == 0) {
    texture_desc->width = size.width();
    texture_desc->height = size.height();
  }

engine/src/flutter/testing/testing.gni (18-19)

Hardcoding enable_unittests = false globally disables unit tests for all platforms, which is a major regression for CI and local testing. Since enable_unittests is a declared argument, it should be overridden in the specific build configuration (e.g., via --args="enable_unittests=false") rather than changing the default value in the source code.

  enable_unittests = current_toolchain == host_toolchain || is_fuchsia || is_mac

engine/src/flutter/tools/gn (91-92)

Simplifying is_host_build to only check args.target_os is None breaks cross-compilation for Linux arm64 and Mac host builds, as explained in the removed comments. Revert this change to preserve support for these platforms.

def is_host_build(args):
  # If target_os == None, then this is a host build.
  if args.target_os is None:
    return True
  # For linux arm64 builds, we cross compile from x64 hosts, so the
  # target_os='linux' and linux-cpu='arm64'
  if args.target_os == 'linux' and args.linux_cpu == 'arm64':
    return True
  # The Mac and host targets are redundant. Again, necessary to disambiguate
  # during cross-compilation.
  if args.target_os == 'mac':
    return True
  return False

engine/src/flutter/txt/src/txt/platform_linux.cc (22-24)

Replacing the default font families globally with only Tizen-specific fonts will break font fallback on standard Linux desktop distributions. Consider prepending the Tizen fonts to the existing list so that both Tizen and standard Linux desktop are supported safely.

std::vector<std::string> GetDefaultFontFamilies() {
  return {"TizenDefaultFont", "SamsungOneUI", "Ubuntu", "Adwaita Sans", "Cantarell",
          "DejaVu Sans", "Liberation Sans", "Arial"};
}

engine/src/flutter/ci/tizen/generate_sysroot.py (44-49)

Using unencrypted HTTP connections to download packages is insecure and vulnerable to man-in-the-middle (MITM) attacks. Use HTTPS instead.

  base_repo = 'https://download.tizen.org/snapshots/TIZEN/Tizen-{}/Tizen-{}-Base/reference/repos/standard/packages'.format(
      api_version, api_version
  )
  unified_repo = 'https://download.tizen.org/snapshots/TIZEN/Tizen-{}/Tizen-{}-Unified/reference/repos/standard/packages'.format(
      api_version, api_version
  )

engine/src/flutter/ci/tizen/generate_sysroot.py (105-108)

Using shell=True with unquoted variables in subprocess.run is unsafe and can fail if paths contain spaces. Avoid shell=True and pass arguments as a list, using Python's open to pass the patch file to stdin safely.

  patch = Path(__file__).parent / '{}.patch'.format(arch)
  if patch.is_file():
    with open(patch, 'r') as f:
      subprocess.run(['patch', '-p1', '-s', '-d', str(sysroot)], stdin=f, check=True)

engine/src/flutter/ci/tizen/Dockerfile (9-11)

To keep the Docker image size small, clean up the apt cache by running rm -rf /var/lib/apt/lists/* after installing packages.

RUN apt-get update && \
    apt-get install -y git zip build-essential cmake ninja-build clang-11 && \
    rm -rf /var/lib/apt/lists/*

engine/src/flutter/ci/tizen/Dockerfile (26-29)

To keep the Docker image size small, clean up the apt cache by running rm -rf /var/lib/apt/lists/* after installing packages.

RUN apt-get update && \
    apt-get install -y binutils-arm-linux-gnueabi binutils-aarch64-linux-gnu binutils-i686-linux-gnu && \
    apt-get install -y git curl pkg-config ca-certificates python3 python3-pip rpm2cpio cpio && \
    rm -rf /var/lib/apt/lists/*

engine/src/flutter/shell/platform/embedder/embedder_external_texture_vulkan.cc (113)

Using kRGB_888x_SkColorType forces the borrowed Skia image to be treated as opaque, discarding any alpha channel. Use kRGBA_8888_SkColorType (similar to the GL external texture implementation) to correctly support transparent external textures.

                                  kRGBA_8888_SkColorType,     // color type