Attempt to improve lifetime management of SkGlyphCache in Ganesh atlas text code.

src/gpu/text/GrAtlasTextBlob.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 GrAtlasTextBlob_DEFINED
 #define GrAtlasTextBlob_DEFINED
 
@@ skipping 238 matching lines @@
     // We use this color vs the SkPaint color because it has the colorfilter applied.
     void initReusableBlob(GrColor color, const SkMatrix& viewMatrix, SkScalar x, SkScalar y) {
         fPaintColor = color;
         this->setupViewMatrix(viewMatrix, x, y);
     }
 
     void initThrowawayBlob(const SkMatrix& viewMatrix, SkScalar x, SkScalar y) {
         this->setupViewMatrix(viewMatrix, x, y);
     }
 
+    /**
+     * Consecutive calls to regenInBatch often use the same SkGlyphCache. If the same instance of
+     * this object is passed to multiple calls to regenInBatch then it can save the cost of multiple
+     * detach/attach operations of SkGlyphCache.
+     */
+    class LazyGlyphCache;
+
     void regenInBatch(GrDrawBatch::Target* target, GrBatchFontCache* fontCache,
-                      GrBlobRegenHelper *helper, int run, int subRun, SkGlyphCache** cache,
-                      SkTypeface** typeface, const SkDescriptor** desc, size_t vertexStride,
-                      const SkMatrix& viewMatrix, SkScalar x, SkScalar y,
-                      GrColor color,
-                      void** vertices, size_t* byteCount, int* glyphCount);
+                      GrBlobRegenHelper *helper, int run, int subRun, LazyGlyphCache*,
+                      size_t vertexStride, const SkMatrix& viewMatrix, SkScalar x, SkScalar y,
+                      GrColor color, void** vertices, size_t* byteCount, int* glyphCount);
 
     const Key& key() const { return fKey; }
 
     ~GrAtlasTextBlob() {
         for (int i = 0; i < fRunCount; i++) {
             fRuns[i].~Run();
         }
     }
 
     ////////////////////////////////////////////////////////////////////////////////////////////////
@@ skipping 207 matching lines @@
         // will be used in place of the run's descriptor to regen texture coords
         SkAutoTDelete<SkAutoDescriptor> fOverrideDescriptor; // df properties
         bool fInitialized;
         bool fDrawAsPaths;
     };
 
     template <bool regenPos, bool regenCol, bool regenTexCoords, bool regenGlyphs>
     void regenInBatch(GrDrawBatch::Target* target,
                       GrBatchFontCache* fontCache,
                       GrBlobRegenHelper* helper,
-                      Run* run, Run::SubRunInfo* info, SkGlyphCache** cache,
-                      SkTypeface** typeface, const SkDescriptor** desc,
-                      int glyphCount, size_t vertexStride,
+                      Run* run, Run::SubRunInfo* info,
+                      LazyGlyphCache*, int glyphCount,
+                      size_t vertexStride,
                       GrColor color, SkScalar transX,
                       SkScalar transY) const;
 
     inline GrDrawBatch* createBatch(const Run::SubRunInfo& info,
                                     int glyphCount, int run, int subRun,
                                     const SkMatrix& viewMatrix, SkScalar x, SkScalar y,
                                     GrColor color,
                                     const SkPaint& skPaint, const SkSurfaceProps& props,
                                     const GrDistanceFieldAdjustTable* distanceAdjustTable,
                                     bool useGammaCorrectDistanceTable,
@@ skipping 42 matching lines @@
 
     // We can reuse distance field text, but only if the new viewmatrix would not result in
     // a mip change.  Because there can be multiple runs in a blob, we track the overall
     // maximum minimum scale, and minimum maximum scale, we can support before we need to regen
     SkScalar fMaxMinScale;
     SkScalar fMinMaxScale;
     int fRunCount;
     uint8_t fTextType;
 };
 
+class GrAtlasTextBlob::LazyGlyphCache {
+public:
+    SkGlyphCache* cache() const { return fCache.get(); }
+
+    void initIfNecessary(Run*, Run::SubRunInfo*);
+private:
+    SkAutoGlyphCache    fCache;
+    const SkTypeface*   fTypeface =  nullptr;
+};
+
 #endif