Cleanup GrDrawTarget now that all paths lead to GrBatch

src/gpu/GrImmediateDrawTarget.h

-/*
- * Copyright 2015 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef GrImmediateDrawTarget_DEFINED
-#define GrImmediateDrawTarget_DEFINED
-
-#include "GrDrawTarget.h"
-
-#include "GrBatchFlushState.h"
-
-/**
- * A debug GrDrawTarget which immediately flushes every command it receives
- */
-class GrImmediateDrawTarget : public GrClipTarget {
-public:
-    /**
-     * Creates a GrImmediateDrawTarget
-     *
-     * @param context    the context object that owns this draw buffer.
-     */
-    GrImmediateDrawTarget(GrContext* context);
-
-    ~GrImmediateDrawTarget() override;
-
-protected:
-    void onDrawBatch(GrBatch*) override;
-
-private:
-    void onReset() override;
-    void onFlush() override;
-
-    uint32_t fDrawID;
-
-    typedef GrClipTarget INHERITED;
-};
-
-#endif