Avoid regenerating cached textblobs on integer scrolls

src/gpu/GrTextBlobCache.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 "GrTextBlobCache.h"
 
 static const int kVerticesPerGlyph = 4;
 
+GrTextBlobCache::~GrTextBlobCache() {
+    SkTDynamicHash<BitmapTextBlob, uint32_t>::Iter iter(&fCache);
+    while (!iter.done()) {
+        (&(*iter))->unref();
+        ++iter;
+    }
+}
+
 GrAtlasTextContext::BitmapTextBlob* GrTextBlobCache::createBlob(int glyphCount, int runCount,
                                                                 size_t maxVASize) {
     // We allocate size for the BitmapTextBlob itself, plus size for the vertices array,
     // and size for the glyphIds array.
     size_t verticesCount = glyphCount * kVerticesPerGlyph * maxVASize;
     size_t size = sizeof(BitmapTextBlob) +
                   verticesCount +
                   glyphCount * sizeof(GrGlyph::PackedID) +
                   sizeof(BitmapTextBlob::Run) * runCount;
 
     BitmapTextBlob* cacheBlob = SkNEW_PLACEMENT(fPool.allocate(size), BitmapTextBlob);
 
     // setup offsets for vertices / glyphs
     cacheBlob->fVertices = sizeof(BitmapTextBlob) + reinterpret_cast<unsigned char*>(cacheBlob);
     cacheBlob->fGlyphIDs =
             reinterpret_cast<GrGlyph::PackedID*>(cacheBlob->fVertices + verticesCount);
     cacheBlob->fRuns = reinterpret_cast<BitmapTextBlob::Run*>(cacheBlob->fGlyphIDs + glyphCount);
 
     // Initialize runs
     for (int i = 0; i < runCount; i++) {
         SkNEW_PLACEMENT(&cacheBlob->fRuns[i], BitmapTextBlob::Run);
     }
     cacheBlob->fRunCount = runCount;
-    cacheBlob->fSize = size;
     cacheBlob->fPool = &fPool;
     return cacheBlob;
 }