Have gpu createTestingOlyBackendTexture know if it is a render target or not

tools/gpu/GrTest.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrTest.h"
 
 #include "GrBatchAtlas.h"
@@ skipping 353 matching lines @@
 
     GrStencilAttachment* createStencilAttachmentForRenderTarget(const GrRenderTarget*,
                                                                 int width,
                                                                 int height) override {
         return nullptr;
     }
 
     void clearStencil(GrRenderTarget* target) override  {}
 
     GrBackendObject createTestingOnlyBackendTexture(void* pixels, int w, int h,
-                                                    GrPixelConfig config) override {
+                                                    GrPixelConfig config, bool isRT) override {
         return 0;
     }
     bool isTestingOnlyBackendTexture(GrBackendObject ) const override { return false; }
     void deleteTestingOnlyBackendTexture(GrBackendObject, bool abandonTexture) override {}
 
     typedef GrGpu INHERITED;
 };
 
 GrContext* GrContext::CreateMockContext() {
     GrContext* context = new GrContext;
 
     context->initMockContext();
     return context;
 }
 
 void GrContext::initMockContext() {
     GrContextOptions options;
     options.fBufferMapThreshold = 0;
     SkASSERT(nullptr == fGpu);
     fGpu = new MockGpu(this, options);
     SkASSERT(fGpu);
     this->initCommon(options);
 
     // We delete these because we want to test the cache starting with zero resources. Also, none of
     // these objects are required for any of tests that use this context. TODO: make stop allocating
     // resources in the buffer pools.
     fDrawingManager->abandon();
 }