Simplify the code to set the background color of the tooltip.

src/VisualStudio/Core/Def.Next/FindReferences/StreamingFindReferencesPresenter.DocumentLocationReferenceEntry.cs

@@ -14,6 +14,8 @@
 using Microsoft.CodeAnalysis.Text.Shared.Extensions;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Extensions;
 using Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem;
+using Microsoft.VisualStudio.PlatformUI;
+using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Shell.TableControl;
 using Microsoft.VisualStudio.Shell.TableManager;
 using Microsoft.VisualStudio.Text;
@@ -140,7 +142,11 @@ private DisposableToolTip CreateDisposableToolTip()
                 var textBuffer = CreateNewBuffer();
 
                 // Create the actual tooltip around the region of that text buffer we want to show.
-                var toolTip = CreateToolTip(textBuffer);
+                var toolTip = new ToolTip
+                {
+                    Content = CreateToolTipContent(textBuffer),
+                    Background = (Brush)Application.Current.Resources[EnvironmentColors.ToolWindowBackgroundBrushKey]
+                };
 
                 // Create a preview workspace for this text buffer and open it's corresponding 
                 // document.  That way we'll get nice things like classification as well as the
@@ -152,21 +158,6 @@ private DisposableToolTip CreateDisposableToolTip()
                 return new DisposableToolTip(toolTip, workspace);
             }
 
-            private ToolTip CreateToolTip(ITextBuffer textBuffer)
-            {
-                var content = CreateToolTipContent(textBuffer);
-
-                var toolTip = new ToolTip { Content = content };
-
-                var style = Presenter._presenterStyles.FirstOrDefault(s => !string.IsNullOrEmpty(s.QuickInfoAppearanceCategory));
-                if (style?.BackgroundBrush != null)
-                {
-                    toolTip.Background = style.BackgroundBrush;
-                }
-
-                return toolTip;
-            }
-
             private ContentControl CreateToolTipContent(ITextBuffer textBuffer)
             {
                 var regionSpan = this.GetRegionSpanForReference();

src/VisualStudio/Core/Def.Next/FindReferences/StreamingFindReferencesPresenter.cs

@@ -39,7 +39,6 @@ internal partial class StreamingFindReferencesPresenter :
         private readonly ClassificationTypeMap _typeMap;
         private readonly IEditorFormatMapService _formatMapService;
         private readonly IFindAllReferencesService _vsFindAllReferencesService;
-        private readonly IEnumerable<QuickInfoPresenterStyle> _presenterStyles;
 
         [ImportingConstructor]
         public StreamingFindReferencesPresenter(
@@ -51,7 +50,6 @@ internal partial class StreamingFindReferencesPresenter :
             IContentTypeRegistryService contentTypeRegistryService,
             ClassificationTypeMap typeMap,
             IEditorFormatMapService formatMapService,
-            [ImportMany] IEnumerable<QuickInfoPresenterStyle> presenterStyles,
             [ImportMany] IEnumerable<Lazy<IAsynchronousOperationListener, FeatureMetadata>> asyncListeners)
         {
             _serviceProvider = serviceProvider;
@@ -63,7 +61,6 @@ internal partial class StreamingFindReferencesPresenter :
             _textEditorFactoryService = textEditorFactoryService;
             _typeMap = typeMap;
             _formatMapService = formatMapService;
-            _presenterStyles = presenterStyles;
 
             _asyncListener = new AggregateAsynchronousOperationListener(
                 asyncListeners, FeatureAttribute.ReferenceHighlighting);