When a surface is backed by an external render target force a copy on image snap

src/gpu/GrGpuResourceCacheAccess.h

 
 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGpuResourceCacheAccess_DEFINED
 #define GrGpuResourceCacheAccess_DEFINED
@@ skipping 13 matching lines @@
     /**
      * Is the resource currently cached as scratch? This means it is cached, has a valid scratch
      * key, and does not have a unique key.
      */
     bool isScratch() const {
         return !fResource->getUniqueKey().isValid() && fResource->fScratchKey.isValid() &&
                 fResource->resourcePriv().isBudgeted();
     }
 
     /**
-     * Is the resource object wrapping an externally allocated GPU resource?
-     */
-    bool isExternal() const { return fResource->isExternal(); }
-
-    /**
      * Is the resource object wrapping an externally allocated GPU resource that Skia has not taken
      * ownership of.
      */
     bool isBorrowed() const { return GrGpuResource::kBorrowed_LifeCycle == fResource->fLifeCycle; }
 
     /**
      * Is the resource object wrapping an externally allocated GPU resource that Skia has taken
      * ownership of.
      */
     bool isAdopted() const { return GrGpuResource::kAdopted_LifeCycle == fResource->fLifeCycle; }
@@ skipping 44 matching lines @@
     friend void test_unbudgeted_to_scratch(skiatest::Reporter* reporter); // for unit testing
 };
 
 inline GrGpuResource::CacheAccess GrGpuResource::cacheAccess() { return CacheAccess(this); }
 
 inline const GrGpuResource::CacheAccess GrGpuResource::cacheAccess() const {
     return CacheAccess(const_cast<GrGpuResource*>(this));
 }
 
 #endif