Revert of Add control of manual mipmapping to GrContextOptions

include/gpu/GrContextOptions.h

Index: include/gpu/GrContextOptions.h
diff --git a/include/gpu/GrContextOptions.h b/include/gpu/GrContextOptions.h
index 59500009715c6913cff2a00c544a273e7fe5dea6..7b62c94a44ce0ba1f1650de81e73dcf03779d3d4 100644
--- a/include/gpu/GrContextOptions.h
+++ b/include/gpu/GrContextOptions.h
@@ -67,11 +67,6 @@
     /** Force us to do all swizzling manually in the shader and don't rely on extensions to do
         swizzling. */
     bool fUseShaderSwizzling;
-
-    /** Construct mipmaps manually, via repeated downsampling draw-calls. This is used when
-        the driver's implementation (glGenerateMipmap) contains bugs. This requires mipmap
-        level and LOD control (ie desktop or ES3). */
-    bool fDoManualMipmapping;
 };
 
 #endif