Don't call finish on GrDrawTarget if we drew no batches

src/gpu/GrDrawTarget.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawTarget.h"
 
 #include "GrAuditTrail.h"
@@ skipping 198 matching lines @@
             fRecordedBatches[i].fBatch->prepare(flushState);
         }
     }
 
     if (fInstancedRendering) {
         fInstancedRendering->beginFlush(flushState->resourceProvider());
     }
 }
 
 void GrDrawTarget::drawBatches(GrBatchFlushState* flushState) {
+    if (0 == fRecordedBatches.count()) {
+        return;
+    }
     // Draw all the generated geometry.
     SkRandom random;
     GrRenderTarget* currentRT = nullptr;
     SkAutoTDelete<GrGpuCommandBuffer> commandBuffer;
     SkRect bounds = SkRect::MakeEmpty();
     for (int i = 0; i < fRecordedBatches.count(); ++i) {
         if (!fRecordedBatches[i].fBatch) {
             continue;
         }
         if (fRecordedBatches[i].fBatch->renderTarget() != currentRT) {
@@ skipping 364 matching lines @@
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void GrDrawTarget::clearStencilClip(const SkIRect& rect, bool insideClip, GrRenderTarget* rt) {
     GrBatch* batch = new GrClearStencilClipBatch(rect, insideClip, rt);
     this->recordBatch(batch, batch->bounds());
     batch->unref();
 }