make tests portable by using 565 compatible colors

gm/shallowgradient.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 "SkGradientShader.h"
 
@@ skipping 34 matching lines @@
 
     SkString onShortName() override {
         return fName;
     }
 
     SkISize onISize() override {
         return SkISize::Make(800, 800);
     }
 
     void onDraw(SkCanvas* canvas) override {
-        const SkColor colors[] = { 0xFF555555, 0xFF444444 };
+        const SkColor colors[] = { sk_tool_utils::color_to_565(0xFF555555), 
+                sk_tool_utils::color_to_565(0xFF444444) };
         const int colorCount = SK_ARRAY_COUNT(colors);
 
         SkRect r = { 0, 0, this->width(), this->height() };
         SkSize size = SkSize::Make(r.width(), r.height());
 
         SkPaint paint;
         paint.setShader(fProc(colors, colorCount, size))->unref();
         canvas->drawRect(r, paint);
     }
 
 private:
     MakeShaderProc fProc;
     SkString fName;
 
     typedef skiagm::GM INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return new ShallowGradientGM(shader_linear, "linear"); )
 DEF_GM( return new ShallowGradientGM(shader_radial, "radial"); )
 DEF_GM( return new ShallowGradientGM(shader_conical, "conical"); )
 DEF_GM( return new ShallowGradientGM(shader_sweep, "sweep"); )