Don't allow nullptr in texels array params (unless using a transfer buffer).

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index ebe4116ebed388ee8277554baa1692a0cacbb607..9725590544fbc599bf91df5317462e764108c623 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -97,21 +97,21 @@ public:
                              const SkTArray<GrMipLevel>& texels);
 
     /**
-     * This function is a shim which creates a SkTArGrMipLevell> of size 1.
-     * It then calls createTexture with that SkTArray.
-     *
-     * @param srcData  texel data to load texture. Begins with full-size
-     *                 palette data for paletted texture. For compressed
-     *                 formats it contains the compressed pixel data. Otherwise,
-     *                 it contains width*height texels. If nullptr texture data
-     *                 is uninitialized.
-     * @param rowBytes the number of bytes between consecutive rows. Zero
-     *                 means rows are tightly packed. This field is ignored
-     *                 for compressed pixel formats.
-     * @return    The texture object if successful, otherwise, nullptr.
+     * Simplified createTexture() interface for when there is no initial texel data to upload.
      */
-    GrTexture* createTexture(const GrSurfaceDesc& desc, SkBudgeted budgeted,
-                             const void* srcData, size_t rowBytes);
+    GrTexture* createTexture(const GrSurfaceDesc& desc, SkBudgeted budgeted) {
+        return this->createTexture(desc, budgeted, SkTArray<GrMipLevel>());
+    }
+
+    /** Simplified createTexture() interface for when there is only a base level */
+    GrTexture* createTexture(const GrSurfaceDesc& desc, SkBudgeted budgeted, const void* level0Data,
+                             size_t rowBytes) {
+        SkASSERT(level0Data);
+        GrMipLevel level = { level0Data, rowBytes };
+        SkSTArray<1, GrMipLevel> array;
+        array.push_back() = level;
+        return this->createTexture(desc, budgeted, array);
+    }
 
     /**
      * Implements GrTextureProvider::wrapBackendTexture