webgl: fix an instance of bugprone-unused-raii

It seems that this constructor call was intended to be used as a scope
guard. In order for that to happen, there has to be a variable name
here.

Bug: 1130379
Change-Id: Iddba99a77b86488298c9ca214cfd0cee92b2ac3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2420920Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808902}

third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc

@@ -5865,7 +5865,7 @@ void WebGLRenderingContextBase::TexImageHelperHTMLVideoElement(
   if (source_image_rect_is_default) {
     // Try using optimized CPU-GPU path for some formats: e.g. Y16 and Y8. It
     // leaves early for other formats or if frame is stored on GPU.
-    ScopedUnpackParametersResetRestore(
+    ScopedUnpackParametersResetRestore unpack_params(
         this, unpack_flip_y_ || unpack_premultiply_alpha_);
     if (video->TexImageImpl(
             static_cast<WebMediaPlayer::TexImageFunctionID>(function_id),