Creating functions for uploading a mipmapped texture.

src/gpu/SkGr.cpp

Index: src/gpu/SkGr.cpp
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 471c9721cf55bd5357dc186a0f6f6f9ea3fd8cc5..6fd1a1090b7cb60a5ad6e82b9d5c6bce89b18bdc 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -19,6 +19,7 @@
 #include "SkErrorInternals.h"
 #include "SkGrPixelRef.h"
 #include "SkMessageBus.h"
+#include "SkMipMap.h"
 #include "SkPixelRef.h"
 #include "SkResourceCache.h"
 #include "SkTextureCompressor.h"
@@ -636,6 +637,37 @@ GrTexture* GrRefCachedBitmapTexture(GrContext* ctx,
     return GrRefCachedBitmapTexture(ctx, bitmap, &params);
 }
 
+GrTexture* GrMipMapTexture(GrContext* ctx,
+                           const SkBitmap& bitmap,
+                           SkDiscardableFactoryProc fact) {
+    // If the SkBitmap is already backed by a texture, we do not want to read the contents back
+    // to the cpu and generate the mipmap only to send it back to the GPU.
+    SkASSERT(!bitmap.getTexture());
+
+    GrSurfaceDesc desc;
+    generate_bitmap_texture_desc(bitmap, &desc);
+
+    auto mipmap = SkMipMap::Build(bitmap, fact);
+    if (mipmap == NULL) {
+        // could not create the mipmap
+        return NULL;
+    } else {
+        auto mipLevelCount = mipmap->getLevelsCount();
+        desc.fIsMipMapped = mipLevelCount > 1;
+        SkTArray<SkMipMapLevel> texels(mipLevelCount);
+        for (int i = 0; i < mipLevelCount; i++) {
+            SkMipMap::Level level;
+            mipmap->getLevel(i, &level);
+
+            SkMipMapLevel currentMipLevel(level.fPixels, level.fRowBytes);
+
+            texels.push_back(currentMipLevel);
+        }
+        return ctx->textureProvider()->createTexture(desc, true, texels);
+        // TODO: BitmapInvalidator support
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 // alphatype is ignore for now, but if GrPixelConfig is expanded to encompass