Fix nullptr access in GrTextureProvider::createMipMappedTexture

src/gpu/GrTextureProvider.cpp

Index: src/gpu/GrTextureProvider.cpp
diff --git a/src/gpu/GrTextureProvider.cpp b/src/gpu/GrTextureProvider.cpp
index f1775aba78f38c869611184cbca3fae00c4842c0..c7ca52867013b7993709f5eb8b23f5cd10e6d105 100644
--- a/src/gpu/GrTextureProvider.cpp
+++ b/src/gpu/GrTextureProvider.cpp
@@ -53,12 +53,17 @@ GrTexture* GrTextureProvider::createMipMappedTexture(const GrSurfaceDesc& desc,
     if (!GrPixelConfigIsCompressed(desc.fConfig) &&
         !desc.fTextureStorageAllocator.fAllocateTextureStorage) {
         if (mipLevelCount < 2) {
-            const GrMipLevel& baseMipLevel = texels[0];
+            const void* basePixels = nullptr;
+            size_t baseRowBytes = 0;
+            if (1 == mipLevelCount) {
+                basePixels = texels[0].fPixels;
+                baseRowBytes = texels[0].fRowBytes;
+            }
             static const uint32_t kFlags = kExact_ScratchTextureFlag |
                                            kNoCreate_ScratchTextureFlag;
             if (GrTexture* texture = this->refScratchTexture(desc, kFlags)) {
                 if (!texels || texture->writePixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
-                                                    baseMipLevel.fPixels, baseMipLevel.fRowBytes)) {
+                                                    basePixels, baseRowBytes)) {
                     if (SkBudgeted::kNo == budgeted) {
                         texture->resourcePriv().makeUnbudgeted();
                     }