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

tests/PictureTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapDevice.h"
 #include "SkBlurImageFilter.h"
 #include "SkCanvas.h"
@@ skipping 712 matching lines @@
         SkAutoTUnref<SkDashPathEffect> dash(SkDashPathEffect::Create(intervals, 2, 0));
 
         SkPaint paint;
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setPathEffect(dash);
 
         canvas->drawPath(path, paint);
     }
     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);
     {
         SkPath path;
 
         path.moveTo(0, 0);
         path.lineTo(0, 50);
         path.lineTo(25, 25);
         path.lineTo(50, 50);
         path.lineTo(50, 0);
@@ skipping 882 matching lines @@
     SkAutoTUnref<SkPicture> picture(recorder.endRecording());
 }
 
 DEF_TEST(Canvas_EmptyBitmap, r) {
     SkBitmap dst;
     dst.allocN32Pixels(10, 10);
     SkCanvas canvas(dst);
 
     test_draw_bitmaps(&canvas);
 }