Remove pixel config fallback - failing is a better option.

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "GrBlurUtils.h"
@@ skipping 153 matching lines @@
     SkColorType ct = origInfo.colorType();
     SkAlphaType at = origInfo.alphaType();
     SkColorSpace* cs = origInfo.colorSpace();
     if (kRGB_565_SkColorType == ct || kGray_8_SkColorType == ct) {
         at = kOpaque_SkAlphaType;  // force this setting
     }
     if (kOpaque_SkAlphaType != at) {
         at = kPremul_SkAlphaType;  // force this setting
     }
 
-    GrPixelConfig origConfig = SkImageInfo2GrPixelConfig(ct, at, cs, *context->caps());
-    if (!context->caps()->isConfigRenderable(origConfig, sampleCount > 0)) {
-        // Fall back from whatever ct was to default of kRGBA or kBGRA which is aliased as kN32
-        ct = kN32_SkColorType;
+    GrPixelConfig config = SkImageInfo2GrPixelConfig(ct, at, cs, *context->caps());
+    if (!context->caps()->isConfigRenderable(config, sampleCount > 0)) {
+        return nullptr;
     }
 
-    GrPixelConfig config = SkImageInfo2GrPixelConfig(ct, at, cs, *context->caps());
-
     return context->makeDrawContext(SkBackingFit::kExact,               // Why exact?
                                     origInfo.width(), origInfo.height(),
                                     config, sk_ref_sp(cs), sampleCount,
                                     origin, surfaceProps, budgeted);
 }
 
 sk_sp<SkSpecialImage> SkGpuDevice::filterTexture(const SkDraw& draw,
                                                  SkSpecialImage* srcImg,
                                                  int left, int top,
                                                  SkIPoint* offset,
@@ skipping 1615 matching lines @@
 }
 
 SkImageFilterCache* SkGpuDevice::getImageFilterCache() {
     ASSERT_SINGLE_OWNER
     // We always return a transient cache, so it is freed after each
     // filter traversal.
     return SkImageFilterCache::Create(kDefaultImageFilterCacheSize);
 }
 
 #endif