Avoid creating full screen clear batches when there is already one in the queue.

src/gpu/batches/GrClearBatch.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 GrClearBatch_DEFINED
 #define GrClearBatch_DEFINED
 
 #include "GrBatch.h"
 #include "GrBatchFlushState.h"
 #include "GrGpu.h"
 #include "GrGpuCommandBuffer.h"
 #include "GrRenderTarget.h"
 
 class GrClearBatch final : public GrBatch {
 public:
     DEFINE_BATCH_CLASS_ID
 
-    static sk_sp<GrBatch> Make(const SkIRect& rect,  GrColor color, GrRenderTarget* rt) {
-        return sk_sp<GrBatch>(new GrClearBatch(rect, color, rt));
+    static sk_sp<GrClearBatch> Make(const SkIRect& rect,  GrColor color, GrRenderTarget* rt) {
+        return sk_sp<GrClearBatch>(new GrClearBatch(rect, color, rt));
     }
 
     const char* name() const override { return "Clear"; }
 
     uint32_t renderTargetUniqueID() const override { return fRenderTarget.get()->getUniqueID(); }
     GrRenderTarget* renderTarget() const override { return fRenderTarget.get(); }
 
     SkString dumpInfo() const override {
         SkString string;
         string.printf("Color: 0x%08x, Rect [L: %d, T: %d, R: %d, B: %d], RT: %d",
                       fColor, fRect.fLeft, fRect.fTop, fRect.fRight, fRect.fBottom,
                       fRenderTarget.get()->getUniqueID());
         string.append(INHERITED::dumpInfo());
         return string;
     }
 
+    void setColor(GrColor color) { fColor = color; }
+
 private:
     GrClearBatch(const SkIRect& rect,  GrColor color, GrRenderTarget* rt)
         : INHERITED(ClassID())
         , fRect(rect)
         , fColor(color)
         , fRenderTarget(rt) {
         this->setBounds(SkRect::Make(rect), HasAABloat::kNo, IsZeroArea::kNo);
     }
 
     bool onCombineIfPossible(GrBatch* t, const GrCaps& caps) override {
@@ skipping 20 matching lines @@
     }
 
     SkIRect                                                 fRect;
     GrColor                                                 fColor;
     GrPendingIOResource<GrRenderTarget, kWrite_GrIOType>    fRenderTarget;
 
     typedef GrBatch INHERITED;
 };
 
 #endif