return and take SkImageGenerator as unique_ptr

BUG=skia:

Change-Id: I4bc11042dd1dbf1eabd40af206027bc65acc3186
Reviewed-on: https://skia-review.googlesource.com/8444
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/tests/CachedDecodingPixelRefTest.cpp b/tests/CachedDecodingPixelRefTest.cpp
index b65765f..d9a9e9e 100644
--- a/tests/CachedDecodingPixelRefTest.cpp
+++ b/tests/CachedDecodingPixelRefTest.cpp
@@ -12,6 +12,7 @@
 #include "SkImage.h"
 #include "SkImageEncoder.h"
 #include "SkImageGenerator.h"
+#include "SkMakeUnique.h"
 #include "SkResourceCache.h"
 #include "SkStream.h"
 #include "SkUtils.h"
@@ -106,8 +107,8 @@
     for (size_t i = 0; i < SK_ARRAY_COUNT(testTypes); ++i) {
         TestImageGenerator::TestType test = testTypes[i];
         for (const SkColorType testColorType : testColorTypes) {
-            SkImageGenerator* gen = new TestImageGenerator(test, r, testColorType);
-            sk_sp<SkImage> image(SkImage::MakeFromGenerator(gen));
+            auto gen = skstd::make_unique<TestImageGenerator>(test, r, testColorType);
+            sk_sp<SkImage> image(SkImage::MakeFromGenerator(std::move(gen)));
             if (nullptr == image) {
                 ERRORF(r, "SkImage::NewFromGenerator unexpecedly failed ["
                     SK_SIZE_T_SPECIFIER "]", i);