don't rely on canvas->readPixels

Bug: skia:3216
Change-Id: I01a8d0083c79c0fe71fbc4d8cfdde4fa6e48b636
Reviewed-on: https://skia-review.googlesource.com/25741
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/tests/ImageNewShaderTest.cpp b/tests/ImageNewShaderTest.cpp
index fe01f04..638fa07 100644
--- a/tests/ImageNewShaderTest.cpp
+++ b/tests/ImageNewShaderTest.cpp
@@ -56,12 +56,12 @@
 
     SkBitmap bmOrig;
     bmOrig.allocN32Pixels(info.width(), info.height());
-    sourceSurface->getCanvas()->readPixels(bmOrig, 0, 0);
+    sourceSurface->readPixels(bmOrig, 0, 0);
 
 
     SkBitmap bm;
     bm.allocN32Pixels(info.width(), info.height());
-    destinationCanvas->readPixels(bm, 0, 0);
+    destinationSurface->readPixels(bm, 0, 0);
 
     test_bitmap_equality(reporter, bmOrig, bm);
 
@@ -83,7 +83,7 @@
 
     SkBitmap bmt;
     bmt.allocN32Pixels(info.width(), info.height());
-    destinationCanvas->readPixels(bmt, 0, 0);
+    destinationSurface->readPixels(bmt, 0, 0);
 
     //  Test correctness
     {