clean up (partially) colortable api

Needs this to land: https://codereview.chromium.org/2789853002/

Bug: skia:
Change-Id: I38d916a546b7fa64d000d973e695ddda24a589e7
Reviewed-on: https://skia-review.googlesource.com/10600
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
diff --git a/samplecode/SampleTinyBitmap.cpp b/samplecode/SampleTinyBitmap.cpp
index 4fb508b..6b01d11 100644
--- a/samplecode/SampleTinyBitmap.cpp
+++ b/samplecode/SampleTinyBitmap.cpp
@@ -19,13 +19,11 @@
     for (int i = 0; i < N; i++) {
         c[i] = SkPackARGB32(0x80, 0x80, 0, 0);
     }
-    SkColorTable* ctable = new SkColorTable(c, N);
 
     SkBitmap bm;
     bm.allocPixels(SkImageInfo::Make(1, 1, kIndex_8_SkColorType,
                                      kPremul_SkAlphaType),
-                   nullptr, ctable);
-    ctable->unref();
+                   SkColorTable::Make(c, N));
 
     bm.lockPixels();
     for (int y = 0; y < bm.height(); y++) {