Change some more GMs to clear to opaque black, not transparent black.

gm/offsetimagefilter.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 "sk_tool_utils.h"
 #include "SkBitmapSource.h"
 #include "SkOffsetImageFilter.h"
@@ skipping 59 matching lines @@
     virtual void onDraw(SkCanvas* canvas) {
         if (!fInitialized) {
             make_bitmap();
 
             fCheckerboard.allocN32Pixels(80, 80);
             SkCanvas checkerboardCanvas(fCheckerboard);
             sk_tool_utils::draw_checkerboard(&checkerboardCanvas, 0xFFA0A0A0, 0xFF404040, 8);
 
             fInitialized = true;
         }
-        canvas->clear(0x00000000);
+        canvas->clear(SK_ColorBLACK);
         SkPaint paint;
 
         for (int i = 0; i < 4; i++) {
             SkBitmap* bitmap = (i & 0x01) ? &fCheckerboard : &fBitmap;
             SkIRect cropRect = SkIRect::MakeXYWH(i * 12,
                                                  i * 8,
                                                  bitmap->width() - i * 8,
                                                  bitmap->height() - i * 12);
             SkImageFilter::CropRect rect(SkRect::Make(cropRect));
             SkAutoTUnref<SkImageFilter> tileInput(SkBitmapSource::Create(*bitmap));
@@ skipping 18 matching lines @@
     SkBitmap fBitmap, fCheckerboard;
     bool fInitialized;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new OffsetImageFilterGM; }
 static GMRegistry reg(MyFactory);
 
 }