Revert of SkThreadPool ~~> SkTaskGroup

src/utils/SkTaskGroup.h

Index: src/utils/SkTaskGroup.h
diff --git a/src/utils/SkTaskGroup.h b/src/utils/SkTaskGroup.h
deleted file mode 100644
index af4d47aa979186a8749821c80100f2b202ce6927..0000000000000000000000000000000000000000
--- a/src/utils/SkTaskGroup.h
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Copyright 2014 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkTaskGroup_DEFINED
-#define SkTaskGroup_DEFINED
-
-#include "SkTypes.h"
-#include "SkRunnable.h"
-
-class SkTaskGroup : SkNoncopyable {
-public:
-    // Call before creating any SkTaskGroup to set the number of threads all SkTaskGroups share.
-    // If not called, we default to the number of system-reported cores.
-    static void SetThreadCount(int);
-
-    SkTaskGroup();
-    ~SkTaskGroup() { this->wait(); }
-
-    // Add a task to this SkTaskGroup.  It will likely run() on another thread.
-    void add(SkRunnable*);
-
-    // Block until all Tasks previously add()ed to this SkTaskGroup have run().
-    // You may safely reuse this SkTaskGroup after wait() returns.
-    void wait();
-
-private:
-    /*atomic*/ int32_t fPending;
-};
-
-#endif//SkTaskGroup_DEFINED