Modifying TextBlobCacheTest to use SkRandomScalerContext

src/gpu/GrBatchFontCache.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 "GrBatchFontCache.h"
 #include "GrContext.h"
 #include "GrFontAtlasSizes.h"
@@ skipping 208 matching lines @@
                                          glyph->width() * bytesPerPixel, expectedMaskFormat,
                                          storage.get())) {
             return false;
         }
     }
 
     bool success = fBatchFontCache->addToAtlas(this, &glyph->fID, batchTarget, expectedMaskFormat,
                                                glyph->width(), glyph->height(),
                                                storage.get(), &glyph->fAtlasLocation);
     if (success) {
+        SkASSERT(GrBatchAtlas::kInvalidAtlasID != glyph->fID);
         fAtlasedGlyphs++;
     }
     return success;
 }