Fix overflow caught by ASAN.

src/codec/SkBmpCodec.h

Index: src/codec/SkBmpCodec.h
diff --git a/src/codec/SkBmpCodec.h b/src/codec/SkBmpCodec.h
index 65662ff1f869df3a655799f93e73598ed57a4a6a..30523b0838dbd2df99c6ae7ac4e558e97eea428a 100644
--- a/src/codec/SkBmpCodec.h
+++ b/src/codec/SkBmpCodec.h
@@ -81,11 +81,6 @@ protected:
     int32_t getDstRow(int32_t y, int32_t height) const;
 
     /*
-     * Compute the number of colors in the color table
-     */
-    uint32_t computeNumColors(uint32_t numColors);
-
-    /*
      * Accessors used by subclasses
      */
     uint16_t bitsPerPixel() const { return fBitsPerPixel; }