Remove parts of //cc we aren't using

cc/resources/task_graph_runner.h

-// Copyright 2014 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 CC_RESOURCES_TASK_GRAPH_RUNNER_H_
-#define CC_RESOURCES_TASK_GRAPH_RUNNER_H_
-
-#include <map>
-#include <vector>
-
-#include "base/logging.h"
-#include "base/memory/ref_counted.h"
-#include "base/synchronization/condition_variable.h"
-#include "cc/base/cc_export.h"
-
-namespace cc {
-
-class CC_EXPORT Task : public base::RefCountedThreadSafe<Task> {
- public:
-  typedef std::vector<scoped_refptr<Task>> Vector;
-
-  virtual void RunOnWorkerThread() = 0;
-
-  void WillRun();
-  void DidRun();
-  bool HasFinishedRunning() const;
-
- protected:
-  friend class base::RefCountedThreadSafe<Task>;
-
-  Task();
-  virtual ~Task();
-
-  bool will_run_;
-  bool did_run_;
-};
-
-// Dependencies are represented as edges in a task graph. Each graph node is
-// assigned a priority and a run count that matches the number of dependencies.
-// Priority range from 0 (most favorable scheduling) to UINT_MAX (least
-// favorable).
-struct CC_EXPORT TaskGraph {
-  struct Node {
-    class TaskComparator {
-     public:
-      explicit TaskComparator(const Task* task) : task_(task) {}
-
-      bool operator()(const Node& node) const { return node.task == task_; }
-
-     private:
-      const Task* task_;
-    };
-
-    typedef std::vector<Node> Vector;
-
-    Node(Task* task, unsigned priority, size_t dependencies)
-        : task(task), priority(priority), dependencies(dependencies) {}
-
-    Task* task;
-    unsigned priority;
-    size_t dependencies;
-  };
-
-  struct Edge {
-    typedef std::vector<Edge> Vector;
-
-    Edge(const Task* task, Task* dependent)
-        : task(task), dependent(dependent) {}
-
-    const Task* task;
-    Task* dependent;
-  };
-
-  TaskGraph();
-  ~TaskGraph();
-
-  void Swap(TaskGraph* other);
-  void Reset();
-
-  Node::Vector nodes;
-  Edge::Vector edges;
-};
-
-class TaskGraphRunner;
-
-// Opaque identifier that defines a namespace of tasks.
-class CC_EXPORT NamespaceToken {
- public:
-  NamespaceToken() : id_(0) {}
-  ~NamespaceToken() {}
-
-  bool IsValid() const { return id_ != 0; }
-
- private:
-  friend class TaskGraphRunner;
-
-  explicit NamespaceToken(int id) : id_(id) {}
-
-  int id_;
-};
-
-// A TaskGraphRunner is used to process tasks with dependencies. There can
-// be any number of TaskGraphRunner instances per thread. Tasks can be scheduled
-// from any thread and they can be run on any thread.
-class CC_EXPORT TaskGraphRunner {
- public:
-  TaskGraphRunner();
-  virtual ~TaskGraphRunner();
-
-  // Returns a unique token that can be used to pass a task graph to
-  // ScheduleTasks(). Valid tokens are always nonzero.
-  NamespaceToken GetNamespaceToken();
-
-  // Schedule running of tasks in |graph|. Tasks previously scheduled but no
-  // longer needed will be canceled unless already running. Canceled tasks are
-  // moved to |completed_tasks| without being run. The result is that once
-  // scheduled, a task is guaranteed to end up in the |completed_tasks| queue
-  // even if it later gets canceled by another call to ScheduleTasks().
-  void ScheduleTasks(NamespaceToken token, TaskGraph* graph);
-
-  // Wait for all scheduled tasks to finish running.
-  void WaitForTasksToFinishRunning(NamespaceToken token);
-
-  // Collect all completed tasks in |completed_tasks|.
-  void CollectCompletedTasks(NamespaceToken token,
-                             Task::Vector* completed_tasks);
-
-  // Run tasks until Shutdown() is called.
-  void Run();
-
-  // Process all pending tasks, but don't wait/sleep. Return as soon as all
-  // tasks that can be run are taken care of.
-  void RunUntilIdle();
-
-  // Signals the Run method to return when it becomes idle. It will continue to
-  // process tasks and future tasks as long as they are scheduled.
-  // Warning: if the TaskGraphRunner remains busy, it may never quit.
-  void Shutdown();
-
- private:
-  struct PrioritizedTask {
-    typedef std::vector<PrioritizedTask> Vector;
-
-    PrioritizedTask(Task* task, unsigned priority)
-        : task(task), priority(priority) {}
-
-    Task* task;
-    unsigned priority;
-  };
-
-  typedef std::vector<const Task*> TaskVector;
-
-  struct TaskNamespace {
-    typedef std::vector<TaskNamespace*> Vector;
-
-    TaskNamespace();
-    ~TaskNamespace();
-
-    // Current task graph.
-    TaskGraph graph;
-
-    // Ordered set of tasks that are ready to run.
-    PrioritizedTask::Vector ready_to_run_tasks;
-
-    // Completed tasks not yet collected by origin thread.
-    Task::Vector completed_tasks;
-
-    // This set contains all currently running tasks.
-    TaskVector running_tasks;
-  };
-
-  typedef std::map<int, TaskNamespace> TaskNamespaceMap;
-
-  static bool CompareTaskPriority(const PrioritizedTask& a,
-                                  const PrioritizedTask& b) {
-    // In this system, numerically lower priority is run first.
-    return a.priority > b.priority;
-  }
-
-  static bool CompareTaskNamespacePriority(const TaskNamespace* a,
-                                           const TaskNamespace* b) {
-    DCHECK(!a->ready_to_run_tasks.empty());
-    DCHECK(!b->ready_to_run_tasks.empty());
-
-    // Compare based on task priority of the ready_to_run_tasks heap .front()
-    // will hold the max element of the heap, except after pop_heap, when max
-    // element is moved to .back().
-    return CompareTaskPriority(a->ready_to_run_tasks.front(),
-                               b->ready_to_run_tasks.front());
-  }
-
-  static bool HasFinishedRunningTasksInNamespace(
-      const TaskNamespace* task_namespace) {
-    return task_namespace->running_tasks.empty() &&
-           task_namespace->ready_to_run_tasks.empty();
-  }
-
-  // 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();
-
-  // This lock protects all members of this class. Do not read or modify
-  // anything without holding this lock. Do not block while holding this lock.
-  mutable base::Lock lock_;
-
-  // Condition variable that is waited on by Run() until new tasks are ready to
-  // run or shutdown starts.
-  base::ConditionVariable has_ready_to_run_tasks_cv_;
-
-  // 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_;
-
-  // Provides a unique id to each NamespaceToken.
-  int next_namespace_id_;
-
-  // This set contains all namespaces with pending, running or completed tasks
-  // not yet collected.
-  TaskNamespaceMap namespaces_;
-
-  // Ordered set of task namespaces that have ready to run tasks.
-  TaskNamespace::Vector ready_to_run_namespaces_;
-
-  // Set during shutdown. Tells Run() to return when no more tasks are pending.
-  bool shutdown_;
-
-  DISALLOW_COPY_AND_ASSIGN(TaskGraphRunner);
-};
-
-}  // namespace cc
-
-#endif  // CC_RESOURCES_TASK_GRAPH_RUNNER_H_