simple fix for preabandon valgrind error

src/gpu/GrAtlasTextContext.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 "GrAtlasTextContext.h"
 
 #include "GrAtlas.h"
 #include "GrBatch.h"
@@ skipping 342 matching lines @@
                                                     bool noGamma) {
     skPaint.getScalerContextDescriptor(&run->fDescriptor, &fDeviceProperties, viewMatrix, noGamma);
     run->fTypeface.reset(SkSafeRef(skPaint.getTypeface()));
     return SkGlyphCache::DetachCache(run->fTypeface, run->fDescriptor.getDesc());
 }
 
 void GrAtlasTextContext::drawTextBlob(GrRenderTarget* rt, const GrClip& clip,
                                       const SkPaint& skPaint, const SkMatrix& viewMatrix,
                                       const SkTextBlob* blob, SkScalar x, SkScalar y,
                                       SkDrawFilter* drawFilter, const SkIRect& clipBounds) {
+    // If we have been abandoned, then don't draw
+    if (!fContext->getTextTarget()) {
+        return;
+    }
+
     SkAutoTUnref<BitmapTextBlob> cacheBlob;
     SkMaskFilter::BlurRec blurRec;
     BitmapTextBlob::Key key;
     // It might be worth caching these things, but its not clear at this time
     // TODO for animated mask filters, this will fill up our cache.  We need a safeguard here
     const SkMaskFilter* mf = skPaint.getMaskFilter();
     bool canCache = !(skPaint.getPathEffect() ||
                       (mf && !mf->asABlur(&blurRec)) ||
                       drawFilter);
 
@@ skipping 1791 matching lines @@
     pipelineBuilder.setFromPaint(grPaint, rt, clip);
 
     GrColor color = grPaint.getColor();
     for (int run = 0; run < cacheBlob->fRunCount; run++) {
         this->flushRun(target, &pipelineBuilder, cacheBlob, run, color, 0, 0, skPaint);
     }
 
     // Now flush big glyphs
     this->flushBigGlyphs(cacheBlob, rt, grPaint, clip, 0, 0);
 }