Add a way for the gpu veto to report back the reason why it said no

BUG=2334
R=bsalomon@google.com

Author: humper@google.com

Review URL: https://codereview.chromium.org/301423002

git-svn-id: http://skia.googlecode.com/svn/trunk@15012 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/PictureTest.cpp b/tests/PictureTest.cpp
index 1ef32ab..d27b463 100644
--- a/tests/PictureTest.cpp
+++ b/tests/PictureTest.cpp
@@ -730,7 +730,10 @@
     }
     SkAutoTUnref<SkPicture> picture(recorder.endRecording());
     // path effects currently render an SkPicture undesireable for GPU rendering
-    REPORTER_ASSERT(reporter, !picture->suitableForGpuRasterization(NULL));
+
+    const char *reason = NULL;
+    REPORTER_ASSERT(reporter, !picture->suitableForGpuRasterization(NULL, &reason));
+    REPORTER_ASSERT(reporter, NULL != reason);
 
     canvas = recorder.beginRecording(100, 100, NULL, 0);
     {