make tests portable by using 565 compatible colors

gm/mipmap.cpp

 /*
  * Copyright 2015 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 "SkCanvas.h"
 #include "SkImage.h"
 #include "SkRandom.h"
 #include "SkSurface.h"
 
 static SkImage* make_image() {
     const SkImageInfo info = SkImageInfo::MakeN32Premul(319, 52);
     SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
     SkCanvas* canvas = surface->getCanvas();
-    canvas->drawColor(0xFFF8F8F8);
+    canvas->drawColor(sk_tool_utils::color_to_565(0xFFF8F8F8));
 
     SkPaint paint;
     paint.setAntiAlias(true);
 
     paint.setStyle(SkPaint::kStroke_Style);
     for (int i = 0; i < 20; ++i) {
         canvas->drawCircle(-4, 25, 20, paint);
         canvas->translate(25, 0);
     }
     return surface->newImageSnapshot();
@@ skipping 30 matching lines @@
 
     void onDraw(SkCanvas* canvas) override {
         test_mip(canvas);
     }
 
 private:
     typedef skiagm::GM INHERITED;
 };
 DEF_GM( return new MipMapGM; )