Add histogram to track number of .nexe launches, normalized against opening n...

base/metrics/nacl_histogram.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// nacl_histogram provides an enum and defines a macro that uses definitions
+// from histogram.h. Note that a histogram is an object that aggregates
+// statistics, and can summarize them in various forms, including ASCII
+// graphical, HTML, and numerically.
+// nacl_histogram information is used to compare how many times a native
+// client module has been loaded, compared to the number of chrome starts
+// and number of new tabs created.
+
+
+#include "base/metrics/histogram.h"
+#include "base/metrics/nacl_histogram.h"
+
+// To log histogram data about NaCl.Startups, call this function with
+// a NaClHistogramValue passed in as |hvalue|
+void UmaNaclHistogramEnumeration(NaClHistogramValue histogram_value) {
+  UMA_HISTOGRAM_ENUMERATION("NaCl.Startups", histogram_value,
+    NACL_MAX_HISTOGRAM);
+}
+