Remove unused zero_fill() in GrAtlas.cpp

src/gpu/GrAtlas.cpp

Index: src/gpu/GrAtlas.cpp
diff --git a/src/gpu/GrAtlas.cpp b/src/gpu/GrAtlas.cpp
index 668a73a6958313430ec4ae243afc95939642d1a4..349b47f620626a22fac6c1038915cb8e008d4200 100644
--- a/src/gpu/GrAtlas.cpp
+++ b/src/gpu/GrAtlas.cpp
@@ -60,11 +60,6 @@ static inline void adjust_for_offset(GrIPoint16* loc, const GrIPoint16& offset)
     loc->fY += offset.fY * GR_ATLAS_HEIGHT;
 }
 
-static inline uint8_t* zero_fill(uint8_t* ptr, size_t count) {
-    sk_bzero(ptr, count);
-    return ptr + count;
-}
-
 bool GrPlot::addSubImage(int width, int height, const void* image,
                           GrIPoint16* loc) {
     if (!fRects->addRect(width, height, loc)) {