Empty picture shaders should draw nothing.

tests/PictureShaderTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
+#include "SkCanvas.h"
 #include "SkPicture.h"
 #include "SkPictureRecorder.h"
 #include "SkShader.h"
 #include "Test.h"
 
 // Test that attempting to create a picture shader with a NULL picture or
-// empty picture returns NULL.
+// empty picture returns a shader that draws nothing.
 DEF_TEST(PictureShader_empty, reporter) {
-    SkShader* shader = SkShader::CreatePictureShader(NULL,
-            SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, NULL, NULL);
-    REPORTER_ASSERT(reporter, NULL == shader);
+    SkPaint paint;
+
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(1,1);
+
+    SkCanvas canvas(bitmap);
+    canvas.clear(SK_ColorGREEN);
+
+    SkShader* shader = SkShader::CreatePictureShader(
+            NULL, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, NULL, NULL);
+    paint.setShader(shader)->unref();
+
+    canvas.drawRect(SkRect::MakeWH(1,1), paint);
+    REPORTER_ASSERT(reporter, *bitmap.getAddr32(0,0) == SK_ColorGREEN);
+
 
     SkPictureRecorder factory;
     factory.beginRecording(0, 0, NULL, 0);
     SkAutoTUnref<SkPicture> picture(factory.endRecording());
-    shader = SkShader::CreatePictureShader(picture.get(),
-            SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, NULL, NULL);
-    REPORTER_ASSERT(reporter, NULL == shader);
+    shader = SkShader::CreatePictureShader(
+            picture.get(), SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, NULL, NULL);
+    paint.setShader(shader)->unref();
+
+    canvas.drawRect(SkRect::MakeWH(1,1), paint);
+    REPORTER_ASSERT(reporter, *bitmap.getAddr32(0,0) == SK_ColorGREEN);
 }