Add passthrough GP for cases where no color or coverage should be emitted by GP

src/gpu/GrAtlasTextContext.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "GrAtlasTextContext.h"
 
 #include "GrBatchFontCache.h"
 #include "GrBatchFlushState.h"
@@ skipping 1563 matching lines @@
         bool usesDistanceFields = this->usesDistanceFields();
         GrMaskFormat maskFormat = this->maskFormat();
         bool isLCD = this->isLCD();
 
         SkAutoTUnref<const GrGeometryProcessor> gp;
         if (usesDistanceFields) {
             gp.reset(this->setupDfProcessor(this->viewMatrix(), fFilteredColor, this->color(),
                                             texture));
         } else {
             GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode);
-            gp.reset(GrBitmapTextGeoProc::Create(this->color(),
-                                                 texture,
-                                                 params,
-                                                 maskFormat,
-                                                 localMatrix,
-                                                 this->usesLocalCoords()));
+            if ((maskFormat == kARGB_GrMaskFormat && fBatch.fColorIgnored)) {
+                gp.reset(GrGeometryProcessor::CreatePassthroughGP(kColorTextVASize));
+            } else {
+                gp.reset(GrBitmapTextGeoProc::Create(this->color(),
+                                                     texture,
+                                                     params,
+                                                     maskFormat,
+                                                     localMatrix,
+                                                     this->usesLocalCoords()));
+            }
         }
 
         FlushInfo flushInfo;
         flushInfo.fGlyphsToFlush = 0;
         size_t vertexStride = gp->getVertexStride();
         SkASSERT(vertexStride == (usesDistanceFields ?
                                   get_vertex_stride_df(maskFormat, isLCD) :
                                   get_vertex_stride(maskFormat)));
 
         target->initDraw(gp, this->pipeline());
@@ skipping 682 matching lines @@
             gTextContext->createDrawTextBlob(rt, clip, grPaint, skPaint, viewMatrix, text,
                                              static_cast<size_t>(textLen), 0, 0, noClip));
 
     SkScalar transX = static_cast<SkScalar>(random->nextU());
     SkScalar transY = static_cast<SkScalar>(random->nextU());
     const GrAtlasTextBlob::Run::SubRunInfo& info = blob->fRuns[0].fSubRunInfo[0];
     return gTextContext->createBatch(blob, info, textLen, 0, 0, color, transX, transY, skPaint);
 }
 
 #endif