Add support for sparse histograms to WebKitPlatformSupportImpl

webkit/glue/webkitplatformsupport_impl.h

Index: webkit/glue/webkitplatformsupport_impl.h
diff --git a/webkit/glue/webkitplatformsupport_impl.h b/webkit/glue/webkitplatformsupport_impl.h
index 0995c6924857854190293a4efcc6e31a7e1d6506..05faab46490248e7d7a443f97a469cd87f19ba75 100644
--- a/webkit/glue/webkitplatformsupport_impl.h
+++ b/webkit/glue/webkitplatformsupport_impl.h
@@ -75,6 +75,7 @@ class WEBKIT_GLUE_EXPORT WebKitPlatformSupportImpl :
     const char* name, int sample, int min, int max, int bucket_count);
   virtual void histogramEnumeration(
     const char* name, int sample, int boundary_value);
+  virtual void histogramSparse(const char* name, int sample);
   virtual const unsigned char* getTraceCategoryEnabledFlag(
       const char* category_name);
   virtual long* getTraceSamplingState(const unsigned thread_bucket);