Revert of TaskGraphRunner Group support

cc/raster/tile_task_worker_pool_perftest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/raster/tile_task_worker_pool.h"
 
 #include "base/test/test_simple_task_runner.h"
 #include "base/time/time.h"
 #include "cc/debug/lap_timer.h"
 #include "cc/output/context_provider.h"
@@ skipping 205 matching lines @@
 
   void BuildTileTaskGraph(TaskGraph* graph,
                           const RasterTaskVector& raster_tasks) {
     size_t priority = 0;
 
     for (auto& raster_task : raster_tasks) {
       priority++;
 
       for (auto& decode_task : raster_task->dependencies()) {
         graph->nodes.push_back(
-            TaskGraph::Node(decode_task.get(), 0u /* group */, priority, 0u));
+            TaskGraph::Node(decode_task.get(), priority, 0u));
         graph->edges.push_back(
             TaskGraph::Edge(raster_task.get(), decode_task.get()));
       }
 
-      graph->nodes.push_back(
-          TaskGraph::Node(raster_task.get(), 0u /* group */, priority,
-                          raster_task->dependencies().size()));
+      graph->nodes.push_back(TaskGraph::Node(
+          raster_task.get(), priority, raster_task->dependencies().size()));
     }
   }
 
  protected:
   scoped_refptr<ContextProvider> context_provider_;
   FakeOutputSurfaceClient output_surface_client_;
   scoped_ptr<FakeOutputSurface> output_surface_;
   scoped_ptr<ResourceProvider> resource_provider_;
   scoped_refptr<base::TestSimpleTaskRunner> task_runner_;
   scoped_ptr<SynchronousTaskGraphRunner> task_graph_runner_;
@@ skipping 245 matching lines @@
   RunBuildTileTaskGraphTest("1_0", 1, 0);
   RunBuildTileTaskGraphTest("32_0", 32, 0);
   RunBuildTileTaskGraphTest("1_1", 1, 1);
   RunBuildTileTaskGraphTest("32_1", 32, 1);
   RunBuildTileTaskGraphTest("1_4", 1, 4);
   RunBuildTileTaskGraphTest("32_4", 32, 4);
 }
 
 }  // namespace
 }  // namespace cc