hide discardable factory from public imagegenerator api

tests/DrawBitmapRectTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkData.h"
 #include "SkDiscardableMemoryPool.h"
-#include "SkImageGenerator.h"
+#include "SkImageGeneratorPriv.h"
 #include "SkMatrixUtils.h"
 #include "SkPaint.h"
 #include "SkRandom.h"
 #include "SkShader.h"
 #include "SkSurface.h"
 #include "Test.h"
 
 // A BitmapFactory that always fails when asked to return pixels.
 class FailureImageGenerator : public SkImageGenerator {
 public:
@@ skipping 291 matching lines @@
 
     // ensure that we draw nothing if srcR does not intersect the bitmap
     REPORTER_ASSERT(reporter, check_for_all_zeros(dst));
 
     test_nan_antihair();
     test_giantrepeat_crbug118018(reporter);
 
     test_treatAsSprite(reporter);
     test_faulty_pixelref(reporter);
 }