store SkAlphaType inside SkBitmap, on road to support unpremul

BUG=
R=bsalomon@google.com, scroggo@google.com

Review URL: https://codereview.chromium.org/25275004

git-svn-id: http://skia.googlecode.com/svn/trunk@11877 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/lazy/SkBitmapFactory.cpp b/src/lazy/SkBitmapFactory.cpp
index 0ff4ee2..5464851 100644
--- a/src/lazy/SkBitmapFactory.cpp
+++ b/src/lazy/SkBitmapFactory.cpp
@@ -53,16 +53,13 @@
         return false;
     }
 
-    bool isOpaque = false;
-    SkBitmap::Config config = SkImageInfoToBitmapConfig(info, &isOpaque);
+    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
 
     Target target;
     // FIMXE: There will be a problem if this rowbytes is calculated differently from
     // in SkLazyPixelRef.
     target.fRowBytes = SkImageMinRowBytes(info);
-
-    dst->setConfig(config, info.fWidth, info.fHeight, target.fRowBytes);
-    dst->setIsOpaque(isOpaque);
+    dst->setConfig(config, info.fWidth, info.fHeight, target.fRowBytes, info.fAlphaType);
 
     // fImageCache and fCacheSelector are mutually exclusive.
     SkASSERT(NULL == fImageCache || NULL == fCacheSelector);