Revert of SkThreadPool ~~> SkTaskGroup

dm/DMTaskRunner.h

Index: dm/DMTaskRunner.h
diff --git a/dm/DMTaskRunner.h b/dm/DMTaskRunner.h
index 3d4e491b9cb298becb4a30a40462cca1b23f28ac..dd1440ed9accb50740ae56193b5045da7bf8582f 100644
--- a/dm/DMTaskRunner.h
+++ b/dm/DMTaskRunner.h
@@ -2,9 +2,11 @@
 #define DMTaskRunner_DEFINED
 
 #include "DMGpuSupport.h"
-#include "SkTDArray.h"
-#include "SkTaskGroup.h"
+#include "SkThreadPool.h"
 #include "SkTypes.h"
+
+// TaskRunner runs Tasks on one of two threadpools depending on the need for a GrContextFactory.
+// It's typically a good idea to run fewer GPU threads than CPU threads (go nuts with those).
 
 namespace DM {
 
@@ -13,15 +15,16 @@
 
 class TaskRunner : SkNoncopyable {
 public:
-    TaskRunner() {}
+    explicit TaskRunner(int cpuThreads, int gpuThreads);
 
     void add(CpuTask* task);
+    void addNext(CpuTask* task);
     void add(GpuTask* task);
     void wait();
 
 private:
-    SkTaskGroup fCpuWork;
-    SkTDArray<GpuTask*> fGpuWork;
+    SkTThreadPool<void> fCpu;
+    SkTThreadPool<GrContextFactory> fGpu;
 };
 
 }  // namespace DM