Add a basic constructor to GrPipeline

Adds a simple constructor for when we just need to set up basic
internal rendering.

BUG=skia:

Change-Id: Ib046c62e9a759aa7d0a3345e16ccf6e6af9342ea
Reviewed-on: https://skia-review.googlesource.com/8121
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/src/gpu/effects/GrPorterDuffXferProcessor.cpp b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
index 8289561..73c6ef4 100644
--- a/src/gpu/effects/GrPorterDuffXferProcessor.cpp
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -900,6 +900,11 @@
     return new PorterDuffXferProcessor(blendFormula);
 }
 
+sk_sp<GrXferProcessor> GrPorterDuffXPFactory::CreateNoCoverageXP(SkBlendMode blendmode) {
+    BlendFormula formula = get_blend_formula(false, false, false, blendmode);
+    return sk_make_sp<PorterDuffXferProcessor>(formula);
+}
+
 bool GrPorterDuffXPFactory::SrcOverWillNeedDstTexture(const GrCaps& caps,
                                                       const GrPipelineAnalysis& analysis) {
     if (caps.shaderCaps()->dstReadInShaderSupport() ||