Add control of manual mipmapping to GrContextOptions

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 260521187a657e7da93a66aa93d25b707842f1ef..7ca2bf9a47e13f58dbd379af152b8261e54a5289 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -551,7 +551,8 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
     // glGenerateMipmap. Our implementation requires mip-level sampling control. Additionally,
     // it can be much slower (especially on mobile GPUs), so we opt-in only when necessary:
     if (fMipMapLevelAndLodControlSupport &&
-        ((kIntel_GrGLVendor == ctxInfo.vendor()) ||
+        (contextOptions.fDoManualMipmapping ||
+         (kIntel_GrGLVendor == ctxInfo.vendor()) ||
          (kNVIDIA_GrGLDriver == ctxInfo.driver() && isMAC) ||
          (kATI_GrGLVendor == ctxInfo.vendor()))) {
         fDoManualMipmapping = true;