Avoid regenerating cached textblobs on integer scrolls

src/gpu/GrTextBlobCache.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextBlobCache_DEFINED
 #define GrTextBlobCache_DEFINED
 
 #include "GrAtlasTextContext.h"
 #include "SkTDynamicHash.h"
 #include "SkTextBlob.h"
 
 class GrTextBlobCache {
 public:
     typedef GrAtlasTextContext::BitmapTextBlob BitmapTextBlob;
 
     GrTextBlobCache() : fPool(kPreAllocSize, kMinGrowthSize) {}
     ~GrTextBlobCache();
 
     // creates an uncached blob
     BitmapTextBlob* createBlob(int glyphCount, int runCount, size_t maxVASize);
+    BitmapTextBlob* createBlob(const SkTextBlob* blob, size_t maxVAStride) {
+        int glyphCount = 0;
+        int runCount = 0;
+        BlobGlyphCount(&glyphCount, &runCount, blob);
+        BitmapTextBlob* cacheBlob = this->createBlob(glyphCount, runCount, maxVAStride);
+        return cacheBlob;
+    }
 
     BitmapTextBlob* createCachedBlob(const SkTextBlob* blob, size_t maxVAStride) {
         int glyphCount = 0;
         int runCount = 0;
         BlobGlyphCount(&glyphCount, &runCount, blob);
         BitmapTextBlob* cacheBlob = this->createBlob(glyphCount, runCount, maxVAStride);
         cacheBlob->fUniqueID = blob->uniqueID();
         this->add(cacheBlob);
         return cacheBlob;
     }
@@ skipping 51 matching lines @@
     // based off of the largest cached textblob I have seen in the skps(a couple of kilobytes).
     static const int kPreAllocSize = 1 << 17;
     static const int kMinGrowthSize = 1 << 17;
     static const int kBudget = 1 << 20;
     BitmapBlobList fBlobList;
     SkTDynamicHash<BitmapTextBlob, uint32_t> fCache;
     GrMemoryPool fPool;
 };
 
 #endif