Add SkCachedData and use it for SkMipMap

src/core/SkBitmapProcState.cpp

Index: src/core/SkBitmapProcState.cpp
diff --git a/src/core/SkBitmapProcState.cpp b/src/core/SkBitmapProcState.cpp
index 6c1dc30449a81ed0a1ddd7686a2cd5eaab5b1a31..4e9a575e02ec0f2f5424544762f197a14fe06669 100644
--- a/src/core/SkBitmapProcState.cpp
+++ b/src/core/SkBitmapProcState.cpp
@@ -260,11 +260,10 @@ bool SkBitmapProcState::possiblyScaleImage() {
     if (scaleSqd > SK_Scalar1) {
         fCurrMip.reset(SkMipMapCache::FindAndRef(fOrigBitmap));
         if (NULL == fCurrMip.get()) {
-            fCurrMip.reset(SkMipMap::Build(fOrigBitmap));
+            fCurrMip.reset(SkMipMapCache::AddAndRef(fOrigBitmap));
             if (NULL == fCurrMip.get()) {
                 return false;
             }
-            SkMipMapCache::Add(fOrigBitmap, fCurrMip);
         }
 
         SkScalar levelScale = SkScalarInvert(SkScalarSqrt(scaleSqd));