Add Sparse Histogram Support to metricsPrivate

chrome/browser/extensions/api/metrics_private/metrics_private_api.h

Index: chrome/browser/extensions/api/metrics_private/metrics_private_api.h
diff --git a/chrome/browser/extensions/api/metrics_private/metrics_private_api.h b/chrome/browser/extensions/api/metrics_private/metrics_private_api.h
index fce8f8801998d4a2f43f45a92ece2cd493af750e..84264167bd58dc667f46c0c5af448104507a4ef1 100644
--- a/chrome/browser/extensions/api/metrics_private/metrics_private_api.h
+++ b/chrome/browser/extensions/api/metrics_private/metrics_private_api.h
@@ -83,6 +83,19 @@ class MetricsPrivateRecordValueFunction
   virtual bool RunImpl() OVERRIDE;
 };
 
+class MetricsPrivateRecordSparseValueFunction
+    : public MetricsHistogramHelperFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("metricsPrivate.recordSparseValue",
+                             METRICSPRIVATE_RECORDSPARSEVALUE)
+
+ protected:
+  virtual ~MetricsPrivateRecordSparseValueFunction() {}
+
+  // ExtensionFunction:
+  virtual bool RunImpl() OVERRIDE;
+};
+
 class MetricsPrivateRecordPercentageFunction
     : public MetricsHistogramHelperFunction {
  public: