Limit lifetime of GrDrawContext objects

src/image/SkImage_Gpu.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkImage_Gpu.h"
 #include "GrContext.h"
@@ skipping 236 matching lines @@
     }
 
     GrPaint paint;
     paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
     paint.addColorFragmentProcessor(GrYUVtoRGBEffect::Create(paint.getProcessorDataManager(),
                                                              yTex, uTex, vTex, yuvSizes,
                                                              colorSpace))->unref();
 
     const SkRect rect = SkRect::MakeWH(SkIntToScalar(dstDesc.fWidth),
                                        SkIntToScalar(dstDesc.fHeight));
-    GrDrawContext* drawContext = ctx->drawContext();
+    SkAutoTUnref<GrDrawContext> drawContext(ctx->drawContext());
+    if (!drawContext) {
+        return nullptr;
+    }
+
     drawContext->drawRect(dst->asRenderTarget(), GrClip::WideOpen(), paint, SkMatrix::I(), rect);
     ctx->flushSurfaceWrites(dst);
     return new SkImage_Gpu(dstDesc.fWidth, dstDesc.fHeight, kNeedNewImageUniqueID,
                            kOpaque_SkAlphaType, dst, 0, budgeted);
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 GrTexture* GrDeepCopyTexture(GrTexture* src, bool budgeted) {
     GrContext* ctx = src->getContext();
 
     GrSurfaceDesc desc = src->desc();
     GrTexture* dst = ctx->textureProvider()->createTexture(desc, budgeted, nullptr, 0);
     if (!dst) {
         return nullptr;
     }
     
     const SkIRect srcR = SkIRect::MakeWH(desc.fWidth, desc.fHeight);
     const SkIPoint dstP = SkIPoint::Make(0, 0);
     ctx->copySurface(dst, src, srcR, dstP, GrContext::kFlushWrites_PixelOp);
     return dst;
 }