display_list: Extract backend-specific surface providers (flutter/engine#56711)

Extracts backend-specific code in DlSurfaceProvider to separate translation units. In particular, this allows for less conditional header includes, and more specifically, allows code relating to the Metal backend to include headers that include ARC-managed Objective-C types. Today we cast these all to void* (and manage refcounting manually) since these headers are included in dl_surface_provider.cc, which is a pure C++ translation unit.

No test changes since this patch includes no semantic changes.

Issue: https://github.com/flutter/flutter/issues/137801

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

engine/src/flutter/display_list/testing/BUILD.gn

@@ -86,6 +86,7 @@ source_set("display_list_surface_provider") {
 
   if (surface_provider_include_software) {
     sources += [
+      "dl_test_surface_provider_software.cc",
       "dl_test_surface_software.cc",
       "dl_test_surface_software.h",
     ]
@@ -95,6 +96,7 @@ source_set("display_list_surface_provider") {
     sources += [
       "dl_test_surface_gl.cc",
       "dl_test_surface_gl.h",
+      "dl_test_surface_provider_gl.cc",
     ]
     deps += [ "//flutter/testing:opengl" ]
   }
@@ -103,6 +105,7 @@ source_set("display_list_surface_provider") {
     sources += [
       "dl_test_surface_metal.h",
       "dl_test_surface_metal.mm",
+      "dl_test_surface_provider_metal.mm",
     ]
     deps += [
       "//flutter/impeller/display_list",

engine/src/flutter/display_list/testing/dl_test_surface_provider.cc

@@ -10,50 +10,29 @@
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/encode/SkPngEncoder.h"
 
-#ifdef ENABLE_SOFTWARE_BENCHMARKS
-#include "flutter/display_list/testing/dl_test_surface_software.h"
-#endif
-#ifdef ENABLE_OPENGL_BENCHMARKS
-#include "flutter/display_list/testing/dl_test_surface_gl.h"
-#endif
-#ifdef ENABLE_METAL_BENCHMARKS
-#include "flutter/display_list/testing/dl_test_surface_metal.h"
-#endif
-
-namespace flutter {
-namespace testing {
+namespace flutter::testing {
 
 std::string DlSurfaceProvider::BackendName(BackendType type) {
   switch (type) {
-    case kMetalBackend:
-      return "Metal";
-    case kOpenGlBackend:
-      return "OpenGL";
     case kSoftwareBackend:
       return "Software";
+    case kOpenGlBackend:
+      return "OpenGL";
+    case kMetalBackend:
+      return "Metal";
   }
 }
 
 std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::Create(
     BackendType backend_type) {
   switch (backend_type) {
-#ifdef ENABLE_SOFTWARE_BENCHMARKS
     case kSoftwareBackend:
-      return std::make_unique<DlSoftwareSurfaceProvider>();
-#endif
-#ifdef ENABLE_OPENGL_BENCHMARKS
-    case kOpenGLBackend:
-      return std::make_unique<DlOpenGLSurfaceProvider>();
-#endif
-#ifdef ENABLE_METAL_BENCHMARKS
+      return CreateSoftware();
+    case kOpenGlBackend:
+      return CreateOpenGL();
     case kMetalBackend:
-      return std::make_unique<DlMetalSurfaceProvider>();
-#endif
-    default:
-      return nullptr;
+      return CreateMetal();
   }
-
-  return nullptr;
 }
 
 bool DlSurfaceProvider::Snapshot(std::string& filename) const {
@@ -78,5 +57,20 @@ bool DlSurfaceProvider::Snapshot(std::string& filename) const {
 #endif
 }
 
-}  // namespace testing
-}  // namespace flutter
+#ifndef ENABLE_SOFTWARE_BENCHMARKS
+std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::CreateSoftware() {
+  return nullptr;
+}
+#endif
+#ifndef ENABLE_OPENGL_BENCHMARKS
+std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::CreateOpenGL() {
+  return nullptr;
+}
+#endif
+#ifndef ENABLE_METAL_BENCHMARKS
+std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::CreateMetal() {
+  return nullptr;
+}
+#endif
+
+}  // namespace flutter::testing

engine/src/flutter/display_list/testing/dl_test_surface_provider.h

@@ -97,6 +97,11 @@ class DlSurfaceProvider {
 
  protected:
   DlSurfaceProvider() = default;
+
+ private:
+  static std::unique_ptr<DlSurfaceProvider> CreateSoftware();
+  static std::unique_ptr<DlSurfaceProvider> CreateMetal();
+  static std::unique_ptr<DlSurfaceProvider> CreateOpenGL();
 };
 
 }  // namespace testing

engine/src/flutter/display_list/testing/dl_test_surface_provider_gl.cc

@@ -0,0 +1,15 @@
+// Copyright 2013 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.
+
+#include "flutter/display_list/testing/dl_test_surface_provider.h"
+
+#include "flutter/display_list/testing/dl_test_surface_gl.h"
+
+namespace flutter::testing {
+
+std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::CreateOpenGL() {
+  return std::make_unique<DlOpenGLSurfaceProvider>();
+}
+
+}  // namespace flutter::testing

engine/src/flutter/display_list/testing/dl_test_surface_provider_metal.mm

@@ -0,0 +1,15 @@
+// Copyright 2013 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.
+
+#include "flutter/display_list/testing/dl_test_surface_provider.h"
+
+#include "flutter/display_list/testing/dl_test_surface_metal.h"
+
+namespace flutter::testing {
+
+std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::CreateMetal() {
+  return std::make_unique<DlMetalSurfaceProvider>();
+}
+
+}  // namespace flutter::testing

engine/src/flutter/display_list/testing/dl_test_surface_provider_software.cc

@@ -0,0 +1,15 @@
+// Copyright 2013 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.
+
+#include "flutter/display_list/testing/dl_test_surface_provider.h"
+
+#include "flutter/display_list/testing/dl_test_surface_software.h"
+
+namespace flutter::testing {
+
+std::unique_ptr<DlSurfaceProvider> DlSurfaceProvider::CreateSoftware() {
+  return std::make_unique<DlSoftwareSurfaceProvider>();
+}
+
+}  // namespace flutter::testing