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/tinybitmap.cpp b/gm/tinybitmap.cpp
index 6cb9ede..92bf7c6 100644
--- a/gm/tinybitmap.cpp
+++ b/gm/tinybitmap.cpp
@@ -18,8 +18,9 @@
     SkColorTable* ctable = new SkColorTable(c, SK_ARRAY_COUNT(c));
 
     SkBitmap bm;
-    bm.setConfig(SkBitmap::kIndex8_Config, 1, 1);
-    bm.allocPixels(ctable);
+    bm.allocPixels(SkImageInfo::Make(1, 1, kIndex_8_SkColorType,
+                                     kPremul_SkAlphaType),
+                   NULL, ctable);
     ctable->unref();
 
     bm.lockPixels();