Some simple optimizations for improving GrAtlasTextContext perf

src/gpu/GrGlyph.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGlyph_DEFINED
 #define GrGlyph_DEFINED
 
@@ skipping 21 matching lines @@
     typedef uint32_t PackedID;
 
     // TODO either plot or AtlasID will be valid, not both
     GrBatchAtlas::AtlasID fID;
     GrPlot*               fPlot;
     SkPath*               fPath;
     PackedID              fPackedID;
     GrMaskFormat          fMaskFormat;
     GrIRect16             fBounds;
     SkIPoint16            fAtlasLocation;
+    bool                  fTooLargeForAtlas;
 
     void init(GrGlyph::PackedID packed, const SkIRect& bounds, GrMaskFormat format) {
         fID = GrBatchAtlas::kInvalidAtlasID;
         fPlot = NULL;
         fPath = NULL;
         fPackedID = packed;
         fBounds.set(bounds);
         fMaskFormat = format;
         fAtlasLocation.set(0, 0);
+        fTooLargeForAtlas = GrBatchAtlas::GlyphTooLargeForAtlas(bounds.width(), bounds.height());
     }
 
     void free() {
         if (fPath) {
             delete fPath;
             fPath = NULL;
         }
     }
 
     int width() const { return fBounds.width(); }
@@ skipping 29 matching lines @@
     
     static inline uint16_t UnpackID(PackedID packed) {
         return (uint16_t)packed;
     }
 
     static inline const GrGlyph::PackedID& GetKey(const GrGlyph& glyph) {
         return glyph.fPackedID;
     }
 
     static inline uint32_t Hash(GrGlyph::PackedID key) {
-        return SkChecksum::Murmur3(&key, sizeof(key));
+        return SkChecksum::Mix(key);
     }
 };
 
 #endif