cc: RenderSurfaceImpl tile mask layer.

cc/output/software_renderer.cc

Index: cc/output/software_renderer.cc
diff --git a/cc/output/software_renderer.cc b/cc/output/software_renderer.cc
index 95fa085ef4a2aa0020838e52ab83ef273d5633b5..75dbff4a6e8ad789ae115f058061baa8a1a1f5b1 100644
--- a/cc/output/software_renderer.cc
+++ b/cc/output/software_renderer.cc
@@ -470,11 +470,7 @@ void SoftwareRenderer::DrawRenderPassQuad(const RenderPassDrawQuad* quad) {
   SkRect dest_visible_rect = gfx::RectFToSkRect(
       MathUtil::ScaleRectProportional(QuadVertexRect(), gfx::RectF(quad->rect),
                                       gfx::RectF(quad->visible_rect)));
-  // TODO(sunxd): make this never be empty.
-  SkRect content_rect =
-      quad->tex_coord_rect.IsEmpty()
-          ? SkRect::MakeWH(quad->rect.width(), quad->rect.height())
-          : RectFToSkRect(quad->tex_coord_rect);
+  SkRect content_rect = RectFToSkRect(quad->tex_coord_rect);
 
   const SkBitmap* content = lock.sk_bitmap();