Revert of TaskGraphRunner Group support

content/renderer/raster_worker_pool.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_RENDERER_RASTER_WORKER_POOL_H_
 #define CONTENT_RENDERER_RASTER_WORKER_POOL_H_
 
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 56 matching lines @@
   // Create a new sequenced task graph runner.
   scoped_refptr<base::SequencedTaskRunner> CreateSequencedTaskRunner();
 
  protected:
   ~RasterWorkerPool() override;
 
  private:
   class RasterWorkerPoolSequencedTaskRunner;
   friend class RasterWorkerPoolSequencedTaskRunner;
 
-  // Run next task. Caller must acquire |lock_| prior to calling this function.
-  // Returns true if there was a task available to run.
-  bool RunTaskWithLockAcquired();
+  // Run next task. Caller must acquire |lock_| prior to calling this function
+  // and make sure at least one task is ready to run.
+  void RunTaskWithLockAcquired();
 
   // Simple Task for the TaskGraphRunner that wraps a closure.
   // This class is used to schedule TaskRunner tasks on the
   // |task_graph_runner_|.
   class ClosureTask : public cc::Task {
    public:
     explicit ClosureTask(const base::Closure& closure);
 
     // Overridden from cc::Task:
     void RunOnWorkerThread() override;
@@ skipping 35 matching lines @@
   // Condition variable that is waited on by origin threads until a namespace
   // has finished running all associated tasks.
   base::ConditionVariable has_namespaces_with_finished_running_tasks_cv_;
   // Set during shutdown. Tells Run() to return when no more tasks are pending.
   bool shutdown_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RASTER_WORKER_POOL_H_