Add a function to convert a texture backed SkImage to raster.

tests/ImageTest.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 <functional>
 #include <initializer_list>
 #include <vector>
@@ skipping 457 matching lines @@
         }
         if (image->width() != texImage->width() || image->height() != texImage->height()) {
             ERRORF(reporter, "newTextureImage changed the image size.");
         }
         if (image->isOpaque() != texImage->isOpaque()) {
             ERRORF(reporter, "newTextureImage changed image opaqueness.");
         }
     }
 }
 
+DEF_GPUTEST_FOR_RENDERING_CONTEXTS(SkImage_makeNonTextureImage, reporter, contextInfo) {
+    GrContext* context = contextInfo.grContext();
+
+    std::function<sk_sp<SkImage>()> imageFactories[] = {
+        create_image,
+        create_codec_image,
+        create_data_image,
+        create_picture_image,
+        [context] { return create_gpu_image(context); },
+    };
+    for (auto factory : imageFactories) {
+        sk_sp<SkImage> image = factory();
+        if (!image->isTextureBacked()) {
+            REPORTER_ASSERT(reporter, image->makeNonTextureImage().get() == image.get());
+            if (!(image = image->makeTextureImage(context))) {
+                continue;
+            }
+        }
+        auto rasterImage = image->makeNonTextureImage();
+        if (!rasterImage) {
+            ERRORF(reporter, "makeNonTextureImage failed for texture-backed image.");
+        }
+        REPORTER_ASSERT(reporter, !rasterImage->isTextureBacked());
+        assert_equal(reporter, image.get(), nullptr, rasterImage.get());
+    }
+}
+
 DEF_GPUTEST_FOR_GL_RENDERING_CONTEXTS(SkImage_drawAbandonedGpuImage, reporter, contextInfo) {
     auto context = contextInfo.grContext();
     auto image = create_gpu_image(context);
     auto info = SkImageInfo::MakeN32(20, 20, kOpaque_SkAlphaType);
     auto surface(SkSurface::MakeRenderTarget(context, SkBudgeted::kNo, info));
     as_IB(image)->peekTexture()->abandon();
     surface->getCanvas()->drawImage(image, 0, 0);
 }
 
 #endif
@@ skipping 448 matching lines @@
                         otherContextInfo.grContext(), buffer, budgeted));
                     REPORTER_ASSERT(reporter, !newImage2);
                     testContext->makeCurrent();
                 }
             }
             sk_free(buffer);
         }
     }
 }
 #endif