Use opaque black not transparent black as imagefilter GM background.

gm/pictureimagefilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 
 #include "SkPictureImageFilter.h"
 #include "SkPictureRecorder.h"
 
 // This GM exercises the SkPictureImageFilter ImageFilter class.
 
 class PictureImageFilterGM : public skiagm::GM {
 public:
     PictureImageFilterGM() {
     }
 
 protected:
     SkString onShortName() override {
         return SkString("pictureimagefilter");
     }
 
     void makePicture() {
         SkPictureRecorder recorder;
         SkCanvas* canvas = recorder.beginRecording(100, 100, NULL, 0);
-        canvas->clear(0x00000000);
+        canvas->clear(SK_ColorBLACK);
         SkPaint paint;
         paint.setAntiAlias(true);
         sk_tool_utils::set_portable_typeface(&paint);
         paint.setColor(0xFFFFFFFF);
         paint.setTextSize(SkIntToScalar(96));
         const char* str = "e";
         canvas->drawText(str, strlen(str), SkIntToScalar(20), SkIntToScalar(70), paint);
         fPicture.reset(recorder.endRecording());
     }
 
     SkISize onISize() override { return SkISize::Make(600, 300); }
 
     void onOnceBeforeDraw() override {
         this->makePicture();
     }
 
     static void fillRectFiltered(SkCanvas* canvas, const SkRect& clipRect, SkImageFilter* filter) {
         SkPaint paint;
         paint.setImageFilter(filter);
         canvas->save();
         canvas->clipRect(clipRect);
         canvas->drawPaint(paint);
         canvas->restore();
     }
 
     void onDraw(SkCanvas* canvas) override {
-        canvas->clear(0x00000000);
+        canvas->clear(SK_ColorBLACK);
         {
             SkRect srcRect = SkRect::MakeXYWH(20, 20, 30, 30);
             SkRect emptyRect = SkRect::MakeXYWH(20, 20, 0, 0);
             SkRect bounds = SkRect::MakeXYWH(0, 0, 100, 100);
             SkAutoTUnref<SkPictureImageFilter> pictureSource(
                 SkPictureImageFilter::Create(fPicture));
             SkAutoTUnref<SkPictureImageFilter> pictureSourceSrcRect(
                 SkPictureImageFilter::Create(fPicture, srcRect));
             SkAutoTUnref<SkPictureImageFilter> pictureSourceEmptyRect(
                 SkPictureImageFilter::Create(fPicture, emptyRect));
@@ skipping 36 matching lines @@
     }
 
 private:
     SkAutoTUnref<SkPicture> fPicture;
     typedef GM INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return new PictureImageFilterGM; )