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

src/gpu/text/GrAtlasTextBlob.h

Index: src/gpu/text/GrAtlasTextBlob.h
diff --git a/src/gpu/text/GrAtlasTextBlob.h b/src/gpu/text/GrAtlasTextBlob.h
index 788eaba77bfb4ffffde2e84ddd994a5475acd4bf..fa3311e07c5ad0f56c5b6f127b77c9f7322cb974 100644
--- a/src/gpu/text/GrAtlasTextBlob.h
+++ b/src/gpu/text/GrAtlasTextBlob.h
@@ -256,12 +256,17 @@ public:
         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; }
 
@@ -489,9 +494,9 @@ private:
     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;
 
@@ -554,4 +559,14 @@ private:
     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