Update libmetrics docs to cover some recent questions and issues.
Review URL: http://codereview.chromium.org/2828017
diff --git a/metrics/metrics_library.h b/metrics/metrics_library.h
index 80bea70..76fa451 100644
--- a/metrics/metrics_library.h
+++ b/metrics/metrics_library.h
@@ -38,6 +38,11 @@
// |nbuckets| is the number of histogram buckets.
// [0,min) is the implicit underflow bucket.
// [|max|,infinity) is the implicit overflow bucket.
+ //
+ // Note that the memory allocated in Chrome for each histogram is
+ // proportional to the number of buckets. Therefore, it is strongly
+ // recommended to keep this number low (e.g., 50 is normal, while
+ // 100 is high).
bool SendToUMA(const std::string& name, int sample,
int min, int max, int nbuckets);
@@ -50,6 +55,12 @@
// |max| is the maximum value of the histogram samples.
// 0 is the implicit underflow bucket.
// [|max|,infinity) is the implicit overflow bucket.
+ //
+ // An enumaration histogram requires |max| + 1 number of
+ // buckets. Note that the memory allocated in Chrome for each
+ // histogram is proportional to the number of buckets. Therefore, it
+ // is strongly recommended to keep this number low (e.g., 50 is
+ // normal, while 100 is high).
bool SendEnumToUMA(const std::string& name, int sample, int max);
// Sends to Autotest and returns true on success.