Cleanup unused method declaration.

Seems the bulk of the code was deleted in
a8f1ac3 with this left over.

BUG=
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1856423002

Cr-Commit-Position: refs/heads/master@{#385203}

cc/output/software_renderer.h

@@ -17,7 +17,6 @@ class RendererClient;
 class ResourceProvider;
 class SoftwareOutputDevice;
 
-class CheckerboardDrawQuad;
 class DebugBorderDrawQuad;
 class PictureDrawQuad;
 class RenderPassDrawQuad;
@@ -74,8 +73,6 @@ class CC_EXPORT SoftwareRenderer : public DirectRenderer {
   void SetClipRect(const gfx::Rect& rect);
   bool IsSoftwareResource(ResourceId resource_id) const;
 
-  void DrawCheckerboardQuad(const DrawingFrame* frame,
-                            const CheckerboardDrawQuad* quad);
   void DrawDebugBorderQuad(const DrawingFrame* frame,
                            const DebugBorderDrawQuad* quad);
   void DrawPictureQuad(const DrawingFrame* frame,