[Flutter GPU] Run unittests on CI and fix HostBuffer. (#49789)

The Flutter GPU tests were broken, and it turns out that I had never set them up to run on CI. This fixes the HostBuffer and gets the test suite running on CI.

Author: bdero

impeller/renderer/BUILD.gn

@@ -149,12 +149,15 @@ impeller_component("renderer_dart_unittests") {
 
   sources = [ "renderer_dart_unittests.cc" ]
 
+  public_configs = [ "//flutter:export_dynamic_symbols" ]
+
   deps = [
     ":renderer",
     "../fixtures:flutter_gpu_fixtures",
     "../fixtures:flutter_gpu_shaders",
     "../playground:playground_test",
     "//flutter/lib/gpu",
+    "//flutter/lib/snapshot",
     "//flutter/runtime:runtime",
     "//flutter/testing:fixture_test",
     "//flutter/testing:testing",

lib/gpu/host_buffer.cc

@@ -31,8 +31,9 @@ size_t HostBuffer::EmplaceBytes(const tonic::DartByteData& byte_data) {
       host_buffer_->Emplace(byte_data.data(), byte_data.length_in_bytes(),
                             impeller::DefaultUniformAlignment());
   emplacements_[current_offset_] = view;
+  size_t previous_offset = current_offset_;
   current_offset_ += view.range.length;
-  return view.range.offset;
+  return previous_offset;
 }
 
 std::optional<impeller::BufferView> HostBuffer::GetBufferViewForOffset(

lib/gpu/host_buffer.h

@@ -48,7 +48,9 @@ class HostBuffer : public RefCountedDartWrappable<HostBuffer> {
 extern "C" {
 
 FLUTTER_GPU_EXPORT
-extern void InternalFlutterGpu_HostBuffer_Initialize(Dart_Handle wrapper);
+extern void InternalFlutterGpu_HostBuffer_Initialize(
+    Dart_Handle wrapper,
+    flutter::gpu::Context* context);
 
 FLUTTER_GPU_EXPORT
 extern size_t InternalFlutterGpu_HostBuffer_EmplaceBytes(

lib/gpu/lib/src/buffer.dart

@@ -161,7 +161,7 @@ base class HostBuffer extends NativeFieldWrapperClass1 with Buffer {
   }
 
   /// Wrap with native counterpart.
-  @Native<Void Function(Handle, Handle)>(
+  @Native<Void Function(Handle, Pointer<Void>)>(
       symbol: 'InternalFlutterGpu_HostBuffer_Initialize')
   external void _initialize(GpuContext gpuContext);
 

testing/run_tests.py

@@ -553,6 +553,16 @@ def make_test(name, flags=None, extra_env=None):
         extra_env=extra_env,
     )
 
+    # Run the Flutter GPU test suite.
+    run_engine_executable(
+        build_dir,
+        'impeller_dart_unittests',
+        executable_filter,
+        shuffle_flags + ['--enable_vulkan_validation'],
+        coverage=coverage,
+        extra_env=extra_env,
+    )
+
 
 def run_engine_benchmarks(build_dir, executable_filter):
   logger.info('Running Engine Benchmarks.')