lock pixels in image when bitmap is immutable and not-lazy

BUG=skia:

Review URL: https://codereview.chromium.org/1266143003
diff --git a/tests/SkImageTest.cpp b/tests/SkImageTest.cpp
index d5c7eaa..fabc1fd 100644
--- a/tests/SkImageTest.cpp
+++ b/tests/SkImageTest.cpp
@@ -26,7 +26,7 @@
         canvas.drawIRect(r, p);
         SkBitmap dstBitmap;
         srcBitmap.extractSubset(&dstBitmap, r);
-        image.reset(SkNewImageFromRasterBitmap(dstBitmap, NULL, kUnlocked_SharedPixelRefMode));
+        image.reset(SkImage::NewFromBitmap(dstBitmap));
     }
 
     SkBitmap tgt;