Revert of implement readPixels and writePixels natively, w/o using the (deprecated)

src/gpu/SkGr.cpp

Index: src/gpu/SkGr.cpp
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index db46b8690126c557d691767e55a5749725dc08ed..94e4c8c35dd4b2e488a16730b584ae8116b15881 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -34,22 +34,11 @@
     SkColorTable* ctable = bitmap.getColorTable();
     char* dst = (char*)buffer;
 
-    const int count = ctable->count();
-
-    SkDstPixelInfo dstPI;
-    dstPI.fColorType = kRGBA_8888_SkColorType;
-    dstPI.fAlphaType = kPremul_SkAlphaType;
-    dstPI.fPixels = buffer;
-    dstPI.fRowBytes = count * sizeof(SkPMColor);
-
-    SkSrcPixelInfo srcPI;
-    srcPI.fColorType = kPMColor_SkColorType;
-    srcPI.fAlphaType = kPremul_SkAlphaType;
-    srcPI.fPixels = ctable->lockColors();
-    srcPI.fRowBytes = count * sizeof(SkPMColor);
-
-    srcPI.convertPixelsTo(&dstPI, count, 1);
-
+    uint32_t* colorTableDst = reinterpret_cast<uint32_t*>(dst);
+    const uint32_t* colorTableSrc = reinterpret_cast<const uint32_t*>(ctable->lockColors());
+    SkConvertConfig8888Pixels(colorTableDst, 0, SkCanvas::kRGBA_Premul_Config8888,
+                              colorTableSrc, 0, SkCanvas::kNative_Premul_Config8888,
+                              ctable->count(), 1);
     ctable->unlockColors();
 
     // always skip a full 256 number of entries, even if we memcpy'd fewer