cc: Remove unused kOnDemandRasterTaskPriority.

cc/resources/raster_worker_pool.cc

Index: cc/resources/raster_worker_pool.cc
diff --git a/cc/resources/raster_worker_pool.cc b/cc/resources/raster_worker_pool.cc
index ad10a1f1dc6a84a9291bf8188aee35a2eac9f344..a720543d1ddc9076a123a79d1f0167d9c1b0ea4f 100644
--- a/cc/resources/raster_worker_pool.cc
+++ b/cc/resources/raster_worker_pool.cc
@@ -88,9 +88,6 @@ class RasterFinishedTaskImpl : public RasterizerTask {
 
 }  // namespace
 
-// This allows an external rasterize on-demand system to run raster tasks
-// with highest priority using the same task graph runner instance.
-unsigned RasterWorkerPool::kOnDemandRasterTaskPriority = 0u;
 // This allows a micro benchmark system to run tasks with highest priority,
 // since it should finish as quickly as possible.
 unsigned RasterWorkerPool::kBenchmarkRasterTaskPriority = 0u;