Sketch DM refactor.

dm/DMTask.h

-#ifndef DMTask_DEFINED
-#define DMTask_DEFINED
-
-#include "DMGpuSupport.h"
-#include "DMReporter.h"
-#include "SkRunnable.h"
-#include "SkTaskGroup.h"
-#include "SkTime.h"
-
-// DM will run() these tasks on one of two threadpools.
-// Subclasses can call fail() to mark this task as failed, or make any number of spawnChild() calls
-// to kick off dependent tasks.
-//
-// Tasks delete themselves when run.
-
-namespace DM {
-
-class TaskRunner;
-
-class CpuTask;
-
-class Task {
-public:
-    virtual bool shouldSkip() const = 0;
-    virtual SkString name() const = 0;
-
-    // Returns the number of parents above this task.
-    // Top-level tasks return 0, their children 1, and so on.
-    int depth() const { return fDepth; }
-
-protected:
-    Task(Reporter* reporter, TaskRunner* taskRunner);
-    Task(const Task& parent);
-    virtual ~Task();
-
-    void start();
-    void fail(const char* msg = NULL);
-    void finish();
-
-    void reallySpawnChild(CpuTask* task);  // For now we don't allow GPU child tasks.
-
-private:
-    Reporter* fReporter;      // Unowned.
-    TaskRunner* fTaskRunner;  // Unowned.
-    int fDepth;
-    SkMSec fStart;
-};
-
-class CpuTask : public Task, public SkRunnable {
-public:
-    CpuTask(Reporter* reporter, TaskRunner* taskRunner);
-    CpuTask(const Task& parent);
-    virtual ~CpuTask() {}
-
-    void run() SK_OVERRIDE;
-    virtual void draw() = 0;
-
-    void spawnChild(CpuTask* task);
-};
-
-class GpuTask : public Task {
- public:
-    GpuTask(Reporter* reporter, TaskRunner* taskRunner);
-    virtual ~GpuTask() {}
-
-    void run(GrContextFactory*);
-    virtual void draw(GrContextFactory*) = 0;
-
-    void spawnChild(CpuTask* task);
-};
-
-}  // namespace DM
-
-#endif  // DMTask_DEFINED