Add a makeDrawContextWithFallback that handles config fallback

src/effects/SkBlurMaskFilter.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMaskFilter.h"
 #include "SkBlurMask.h"
 #include "SkGpuBlurUtils.h"
@@ skipping 1103 matching lines @@
                     SkRRect::kLowerRight_Corner, SkRRect::kLowerLeft_Corner }) {
         SkASSERT(SkScalarIsInt(rrectToDraw.radii(c).fX) && SkScalarIsInt(rrectToDraw.radii(c).fY));
         builder[index++] = SkScalarCeilToInt(rrectToDraw.radii(c).fX);
         builder[index++] = SkScalarCeilToInt(rrectToDraw.radii(c).fY);
     }
     builder.finish();
 
     sk_sp<GrTexture> mask(context->textureProvider()->findAndRefTextureByUniqueKey(key));
     if (!mask) {
         // TODO: this could be approx but the texture coords will need to be updated
-        sk_sp<GrDrawContext> dc(context->makeDrawContext(SkBackingFit::kExact,
-                                                         size.fWidth, size.fHeight,
-                                                         kAlpha_8_GrPixelConfig, nullptr));
+        sk_sp<GrDrawContext> dc(context->makeDrawContextWithFallback(SkBackingFit::kExact,
+                                                                     size.fWidth, size.fHeight,
+                                                                     kAlpha_8_GrPixelConfig,
+                                                                     nullptr));
         if (!dc) {
             return nullptr;
         }
                 
         GrPaint grPaint;
         grPaint.setAntiAlias(doAA);
 
         dc->clear(nullptr, 0x0, true);
         dc->drawRRect(GrNoClip(), grPaint, SkMatrix::I(), rrectToDraw, GrStyle::SimpleFill());
 
@@ skipping 425 matching lines @@
     } else {
         str->append("None");
     }
     str->append("))");
 }
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkBlurMaskFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurMaskFilterImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END