hide SkBitmap::Config entirely (behind a flag)

patch from issue 339463002

TBR=

I think the NoGPU failure is unrelated, so ignoring
NOTRY=True

Author: reed@google.com

Review URL: https://codereview.chromium.org/340533002
diff --git a/src/animator/SkDrawBitmap.cpp b/src/animator/SkDrawBitmap.cpp
index ce96efb..f481ee7 100644
--- a/src/animator/SkDrawBitmap.cpp
+++ b/src/animator/SkDrawBitmap.cpp
@@ -56,7 +56,7 @@
 
 DEFINE_GET_MEMBER(SkDrawBitmap);
 
-SkDrawBitmap::SkDrawBitmap() : format((SkBitmap::Config) -1), height(-1),
+SkDrawBitmap::SkDrawBitmap() : format((SkColorType) -1), height(-1),
     rowBytes(0),    width(-1), fColor(0), fColorSet(false) {
 }
 
@@ -88,7 +88,7 @@
     SkASSERT(width != -1);
     SkASSERT(height != -1);
     SkASSERT(rowBytes >= 0);
-    SkColorType colorType = SkBitmapConfigToColorType((SkBitmap::Config)format);
+    SkColorType colorType = SkColorType(format);
     fBitmap.setInfo(SkImageInfo::Make(width, height, colorType, kPremul_SkAlphaType), rowBytes);
     fBitmap.allocPixels();
     if (fColorSet)