cc: Move SkShader construction to a single spot in PaintShader

cc/paint/discardable_image_map_unittest.cc

Index: cc/paint/discardable_image_map_unittest.cc
diff --git a/cc/paint/discardable_image_map_unittest.cc b/cc/paint/discardable_image_map_unittest.cc
index 5457d581eebc39500dafeb540972d5880c698b94..12559c55afb44bacf68b9681af8838b44bdb9439 100644
--- a/cc/paint/discardable_image_map_unittest.cc
+++ b/cc/paint/discardable_image_map_unittest.cc
@@ -600,8 +600,9 @@ TEST_F(DiscardableImageMapTest, GetDiscardableImagesInShader) {
         SkMatrix scale = SkMatrix::MakeScale(std::max(x * 0.5f, kMinScale),
                                              std::max(y * 0.5f, kMinScale));
         PaintFlags flags;
-        flags.setShader(discardable_image[y][x]->makeShader(
-            SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, &scale));
+        flags.setShader(base::MakeUnique<PaintShader>(
+            discardable_image[y][x], SkShader::kClamp_TileMode,
+            SkShader::kClamp_TileMode, &scale));
         content_layer_client.add_draw_rect(
             gfx::Rect(x * 512 + 6, y * 512 + 6, 500, 500), flags);
       }