SkImage method for detecting lazy decoding

BUG=skia:4224
R=reed@google.com

Review URL: https://codereview.chromium.org/1305453007
diff --git a/tests/CachedDecodingPixelRefTest.cpp b/tests/CachedDecodingPixelRefTest.cpp
index 0e9b18e..c69cd96 100644
--- a/tests/CachedDecodingPixelRefTest.cpp
+++ b/tests/CachedDecodingPixelRefTest.cpp
@@ -326,6 +326,7 @@
         }
         REPORTER_ASSERT(r, TestImageGenerator::Width() == image->width());
         REPORTER_ASSERT(r, TestImageGenerator::Height() == image->height());
+        REPORTER_ASSERT(r, image->isLazyGenerated());
 
         SkBitmap bitmap;
         bitmap.allocN32Pixels(TestImageGenerator::Width(), TestImageGenerator::Height());