Move GrDrawTarget::clear logic into GrDrawContext

src/gpu/batches/GrClearStencilClipBatch.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrClearStencilClipBatch_DEFINED
+#define GrClearStencilClipBatch_DEFINED
+
+#include "GrBatch.h"
+#include "GrBatchFlushState.h"
+#include "GrGpu.h"
+#include "GrGpuCommandBuffer.h"
+#include "GrRenderTarget.h"
+
+class GrClearStencilClipBatch final : public GrBatch {
+public:
+    DEFINE_BATCH_CLASS_ID
+
+    GrClearStencilClipBatch(const SkIRect& rect, bool insideClip, GrRenderTarget* rt)
+        : INHERITED(ClassID())
+        , fRect(rect)
+        , fInsideClip(insideClip)
+        , fRenderTarget(rt) {
+        this->setBounds(SkRect::Make(rect), HasAABloat::kNo, IsZeroArea::kNo);
+    }
+
+    const char* name() const override { return "ClearStencilClip"; }
+
+    uint32_t renderTargetUniqueID() const override { return fRenderTarget.get()->getUniqueID(); }
+    GrRenderTarget* renderTarget() const override { return fRenderTarget.get(); }
+
+    SkString dumpInfo() const override {
+        SkString string;
+        string.printf("Rect [L: %d, T: %d, R: %d, B: %d], IC: %d, RT: %d",
+                      fRect.fLeft, fRect.fTop, fRect.fRight, fRect.fBottom, fInsideClip,
+                      fRenderTarget.get()->getUniqueID());
+        string.append(INHERITED::dumpInfo());
+        return string;
+    }
+
+private:
+    bool onCombineIfPossible(GrBatch* t, const GrCaps& caps) override { return false; }
+
+    void onPrepare(GrBatchFlushState*) override {}
+
+    void onDraw(GrBatchFlushState* state) override {
+        state->commandBuffer()->clearStencilClip(fRect, fInsideClip, fRenderTarget.get());
+    }
+
+    SkIRect                                                 fRect;
+    bool                                                    fInsideClip;
+    GrPendingIOResource<GrRenderTarget, kWrite_GrIOType>    fRenderTarget;
+
+    typedef GrBatch INHERITED;
+};
+
+#endif