store SkAlphaType inside SkBitmap, on road to support unpremul

bench/BitmapScaleBench.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 "SkBenchmark.h"
 #include "SkCanvas.h"
 #include "SkPaint.h"
@@ skipping 39 matching lines @@
 
     SkIPoint onGetSize() SK_OVERRIDE {
         return SkIPoint::Make( fOutputSize, fOutputSize );
     }
 
     void setName(const char * name) {
         fName.printf( "bitmap_scale_%s_%d_%d", name, fInputSize, fOutputSize );
     }
 
     virtual void onPreDraw() {
-        fInputBitmap.setConfig(SkBitmap::kARGB_8888_Config, fInputSize, fInputSize);
+        fInputBitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                               fInputSize, fInputSize, 0, kOpaque_SkAlphaType);
         fInputBitmap.allocPixels();
         fInputBitmap.eraseColor(SK_ColorWHITE);
-        fInputBitmap.setIsOpaque(true);
 
-        fOutputBitmap.setConfig(SkBitmap::kARGB_8888_Config, fOutputSize, fOutputSize);
+        fOutputBitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                                fOutputSize, fOutputSize, 0, kOpaque_SkAlphaType);
         fOutputBitmap.allocPixels();
-        fOutputBitmap.setIsOpaque(true);
 
         fMatrix.setScale( scale(), scale() );
     }
 
     virtual void onDraw(SkCanvas*) {
         SkPaint paint;
         this->setupPaint(&paint);
 
         preBenchSetup();
 
@@ skipping 27 matching lines @@
 
 DEF_BENCH(return new BitmapFilterScaleBench(10, 90);)
 DEF_BENCH(return new BitmapFilterScaleBench(30, 90);)
 DEF_BENCH(return new BitmapFilterScaleBench(80, 90);)
 DEF_BENCH(return new BitmapFilterScaleBench(90, 90);)
 DEF_BENCH(return new BitmapFilterScaleBench(90, 80);)
 DEF_BENCH(return new BitmapFilterScaleBench(90, 30);)
 DEF_BENCH(return new BitmapFilterScaleBench(90, 10);)
 DEF_BENCH(return new BitmapFilterScaleBench(256, 64);)
 DEF_BENCH(return new BitmapFilterScaleBench(64, 256);)