add new copyTo version to SkBitmap, which takes SkColorType

BUG=skia:
R=scroggo@google.com, halcanary@google.com, bsalomon@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/171723007

git-svn-id: http://skia.googlecode.com/svn/trunk@13553 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/bitmapfilters.cpp b/gm/bitmapfilters.cpp
index 7addf25..fb3b304 100644
--- a/gm/bitmapfilters.cpp
+++ b/gm/bitmapfilters.cpp
@@ -85,9 +85,9 @@
         }
         fOnce = true;
         make_bm(&fBM8);
-        fBM8.copyTo(&fBM4444, SkBitmap::kARGB_4444_Config);
-        fBM8.copyTo(&fBM16, SkBitmap::kRGB_565_Config);
-        fBM8.copyTo(&fBM32, SkBitmap::kARGB_8888_Config);
+        fBM8.copyTo(&fBM4444, kARGB_4444_SkColorType);
+        fBM8.copyTo(&fBM16, kRGB_565_SkColorType);
+        fBM8.copyTo(&fBM32, kPMColor_SkColorType);
     }
 public:
     SkBitmap    fBM8, fBM4444, fBM16, fBM32;