Add SkSourceGammaTreatment enum so we know how to create mips

gm/image_pict.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"
@@ skipping 298 matching lines @@
     static void draw_as_bitmap(SkCanvas* canvas, SkImageCacherator* cache, SkScalar x, SkScalar y) {
         SkBitmap bitmap;
         cache->lockAsBitmap(&bitmap, nullptr);
         canvas->drawBitmap(bitmap, x, y);
     }
 
     static void draw_as_tex(SkCanvas* canvas, SkImageCacherator* cache, SkScalar x, SkScalar y) {
 #if SK_SUPPORT_GPU
         SkAutoTUnref<GrTexture> texture(cache->lockAsTexture(canvas->getGrContext(),
                                                              GrTextureParams::ClampBilerp(),
+                                                             SkSourceGammaTreatment::kRespect,
                                                              nullptr));
         if (!texture) {
             // show placeholder if we have no texture
             SkPaint paint;
             paint.setStyle(SkPaint::kStroke_Style);
             SkRect r = SkRect::MakeXYWH(x, y, SkIntToScalar(cache->info().width()),
                                         SkIntToScalar(cache->info().width()));
             canvas->drawRect(r, paint);
             canvas->drawLine(r.left(), r.top(), r.right(), r.bottom(), paint);
             canvas->drawLine(r.left(), r.bottom(), r.right(), r.top(), paint);
@@ skipping 43 matching lines @@
 
 private:
     typedef skiagm::GM INHERITED;
 };
 DEF_GM( return new ImageCacheratorGM("picture", make_pic_generator); )
 DEF_GM( return new ImageCacheratorGM("raster", make_ras_generator); )
 DEF_GM( return new ImageCacheratorGM("ctable", make_ctable_generator); )
 #if SK_SUPPORT_GPU
     DEF_GM( return new ImageCacheratorGM("texture", make_tex_generator); )
 #endif