use SkImageInfo directly, instead of converting to SkBitmap::Config

src/image/SkSurface_Base.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSurface_Base_DEFINED
 #define SkSurface_Base_DEFINED
 
 #include "SkSurface.h"
 #include "SkCanvas.h"
 
 class SkSurface_Base : public SkSurface {
 public:
     SkSurface_Base(int width, int height);
+    explicit SkSurface_Base(const SkImageInfo&);
     virtual ~SkSurface_Base();
 
     /**
      *  Allocate a canvas that will draw into this surface. We will cache this
      *  canvas, to return the same object to the caller multiple times. We
      *  take ownership, and will call unref() on the canvas when we go out of
      *  scope.
      */
     virtual SkCanvas* onNewCanvas() = 0;
 
@@ skipping 60 matching lines @@
     return fCachedImage;
 }
 
 void SkSurface_Base::installIntoCanvasForDirtyNotification() {
     if (NULL != fCachedCanvas) {
         fCachedCanvas->setSurfaceBase(this);
     }
 }
 
 #endif