replace SkBitmap::Config with SkColorType in gms

add helper installMaskPixels() to SkBitmap

BUG=skia:
R=halcanary@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/169913003

git-svn-id: http://skia.googlecode.com/svn/trunk@13482 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/simpleaaclip.cpp b/gm/simpleaaclip.cpp
index e8946b4..a517b50 100644
--- a/gm/simpleaaclip.cpp
+++ b/gm/simpleaaclip.cpp
@@ -21,9 +21,7 @@
 
     SkAutoMaskFreeImage amfi(mask.fImage);
 
-    bm.setConfig(SkBitmap::kA8_Config, mask.fBounds.width(),
-                 mask.fBounds.height(), mask.fRowBytes);
-    bm.setPixels(mask.fImage);
+    bm.installMaskPixels(mask);
 
     // need to copy for deferred drawing test to work
     SkBitmap bm2;