respect srgb gamma when building mips

bench/MipMapBench.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 "Benchmark.h"
 #include "SkBitmap.h"
 #include "SkMipMap.h"
 
 class MipMapBench: public Benchmark {
     SkBitmap fBitmap;
     SkString fName;
     const int fW, fH;
+    SkMipMap::SrcGammaMode fMode;
 
 public:
-    MipMapBench(int w, int h) : fW(w), fH(h) {
-        fName.printf("mipmap_build_%dx%d", w, h);
+    MipMapBench(int w, int h, SkMipMap::SrcGammaMode mode) : fW(w), fH(h), fMode(mode) {
+        fName.printf("mipmap_build_%dx%d_%d_gamma", w, h, mode);
     }
 
 protected:
     bool isSuitableFor(Backend backend) override {
         return kNonRendering_Backend == backend;
     }
 
     const char* onGetName() override { return fName.c_str(); }
 
     void onDelayedSetup() override {
-        fBitmap.allocN32Pixels(fW, fH, true);
+        SkImageInfo info = SkImageInfo::MakeS32(fW, fH, kPremul_SkAlphaType);
+        fBitmap.allocPixels(info);
         fBitmap.eraseColor(SK_ColorWHITE);  // so we don't read uninitialized memory
     }
 
     void onDraw(int loops, SkCanvas*) override {
         for (int i = 0; i < loops * 4; i++) {
-            SkMipMap::Build(fBitmap, nullptr)->unref();
+            SkMipMap::Build(fBitmap, fMode, nullptr)->unref();
         }
     }
 
 private:
     typedef Benchmark INHERITED;
 };
 
 // Build variants that exercise the width and heights being even or odd at each level, as the
 // impl specializes on each of these.
 //
-DEF_BENCH( return new MipMapBench(511, 511); )
-DEF_BENCH( return new MipMapBench(512, 511); )
-DEF_BENCH( return new MipMapBench(511, 512); )
-DEF_BENCH( return new MipMapBench(512, 512); )
+DEF_BENCH( return new MipMapBench(511, 511, SkMipMap::kIgnore_SrcGammaMode); )
+DEF_BENCH( return new MipMapBench(512, 511, SkMipMap::kIgnore_SrcGammaMode); )
+DEF_BENCH( return new MipMapBench(511, 512, SkMipMap::kIgnore_SrcGammaMode); )
+DEF_BENCH( return new MipMapBench(512, 512, SkMipMap::kIgnore_SrcGammaMode); )
+DEF_BENCH( return new MipMapBench(512, 512, SkMipMap::kRespect_SrcGammaMode); )