Move some work from backend onClear to base class clear

src/gpu/GrImmediateDrawTarget.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrImmediateDrawTarget.h"
 
 #include "GrBatch.h"
@@ skipping 31 matching lines @@
     batch->generateGeometry(&fBatchTarget);
     batch->setNumberOfDraws(fBatchTarget.numberOfDraws());
 
     fBatchTarget.preFlush();
     fBatchTarget.flushNext(batch->numberOfDraws());
     fBatchTarget.postFlush();
 
     pipeline->~GrPipeline();
 }
 
-void GrImmediateDrawTarget::onClear(const SkIRect* rect, GrColor color,
-                                    bool canIgnoreRect, GrRenderTarget* renderTarget) {
-    this->getGpu()->clear(rect, color, canIgnoreRect, renderTarget);
+void GrImmediateDrawTarget::onClear(const SkIRect& rect, GrColor color,
+                                    GrRenderTarget* renderTarget) {
+    this->getGpu()->clear(rect, color, renderTarget);
 }
 
 void GrImmediateDrawTarget::onCopySurface(GrSurface* dst,
                                           GrSurface* src,
                                           const SkIRect& srcRect,
                                           const SkIPoint& dstPoint) {
     this->getGpu()->copySurface(dst, src, srcRect, dstPoint);
 }
 
 void GrImmediateDrawTarget::clearStencilClip(const SkIRect& rect,
@@ skipping 33 matching lines @@
 
 void GrImmediateDrawTarget::recordXferBarrierIfNecessary(const GrPipeline* pipeline) {
     const GrXferProcessor& xp = *pipeline->getXferProcessor();
     GrRenderTarget* rt = pipeline->getRenderTarget();
 
     GrXferBarrierType barrierType;
     if (xp.willNeedXferBarrier(rt, *this->caps(), &barrierType)) {
         this->getGpu()->xferBarrier(rt, barrierType);
     }
 }