Migrate more GL calls of GrBackend* (flutter/engine#44682)

Follow-up to https://github.com/flutter/engine/pull/44334

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [x] I added new tests to check the change I am making or feature I am
adding, or Hixie said the PR is test-exempt. See [testing the engine]
for instructions on writing and running engine tests.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I signed the [CLA].
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#overview
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[C++, Objective-C, Java style guides]:
https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
[testing the engine]:
https://github.com/flutter/flutter/wiki/Testing-the-engine
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes
[Discord]: https://github.com/flutter/flutter/wiki/Chat

engine/src/flutter/lib/web_ui/skwasm/image.cpp

@@ -17,6 +17,7 @@
 #include "third_party/skia/include/gpu/ganesh/GrExternalTextureGenerator.h"
 #include "third_party/skia/include/gpu/ganesh/SkImageGanesh.h"
 #include "third_party/skia/include/gpu/ganesh/SkSurfaceGanesh.h"
+#include "third_party/skia/include/gpu/ganesh/gl/GrGLBackendSurface.h"
 #include "third_party/skia/include/gpu/gl/GrGLInterface.h"
 #include "third_party/skia/include/gpu/gl/GrGLTypes.h"
 
@@ -100,8 +101,8 @@ class VideoFrameImageGenerator : public GrExternalTextureGenerator {
     glInfo.fFormat = GL_RGBA8_OES;
     glInfo.fTarget = GL_TEXTURE_2D;
 
-    GrBackendTexture backendTexture(fInfo.width(), fInfo.height(), mipmapped,
-                                    glInfo);
+    auto backendTexture = GrBackendTextures::MakeGL(
+        fInfo.width(), fInfo.height(), mipmapped, glInfo);
     return std::make_unique<ExternalWebGLTexture>(
         backendTexture, glInfo.fID, emscripten_webgl_get_current_context());
   }

engine/src/flutter/lib/web_ui/skwasm/surface.cpp

@@ -6,6 +6,7 @@
 
 #include "third_party/skia/include/gpu/GrBackendSurface.h"
 #include "third_party/skia/include/gpu/GrDirectContext.h"
+#include "third_party/skia/include/gpu/ganesh/gl/GrGLBackendSurface.h"
 
 using namespace Skwasm;
 
@@ -155,8 +156,8 @@ void Surface::_setCanvasSize(int width, int height) {
 // Worker thread only
 void Surface::_recreateSurface() {
   makeCurrent(_glContext);
-  GrBackendRenderTarget target(_canvasWidth, _canvasHeight, _sampleCount,
-                               _stencil, _fbInfo);
+  auto target = GrBackendRenderTargets::MakeGL(_canvasWidth, _canvasHeight,
+                                               _sampleCount, _stencil, _fbInfo);
   _surface = SkSurfaces::WrapBackendRenderTarget(
       _grContext.get(), target, kBottomLeft_GrSurfaceOrigin,
       kRGBA_8888_SkColorType, SkColorSpace::MakeSRGB(), nullptr);